AF Amplifier With Digital Volume Control Based On TDA8551

The Philips Semiconductors TDA8551 is a small audio amplifier with an integrated volume control. When operated from +5 V, it delivers a nominal output power of more than one watt into 8 ohms. It can also be used over a supply voltage range of +2.7 to +5.5 V, with correspondingly reduced output power. The output volume can be adjusted from –60 dB to +20 dB in 64 steps, using a set of up and down push-buttons. The shared UP/DOWN input for the up and down switches has three states. If it is ‘floating’, which means that both of the switches are open, the volume remains unchanged. A pulse to earth decreases the volume by 1.25 dB, while a positive pulse increases the volume by 1.25 dB.

When the power is switched on, the internal counter takes on the –20 dB setting. An additional input (MODE) allows the amplifier to be switched from the operating state to the mute or standby state. If this input is held at the earth level, the amplifier is operational. If +5 V is applied to this pin, the TDA8551 enters the Standby mode, in which the current consumption drops from the typical operational level of 6mA to less than 10µA. Finally, the MODE input can be used as a mute input by applying a voltage of 1 t0 3.6 V to this input. This voltage can be provided by a connection to the SCR pin, which lies at half of the operating voltage and to which a filter capacitor is connected.

The loudspeaker is connected in a floating configuration between the two outputs of the bridge amplifier in the TDA8551. This provides the desired output power level, in spite of the low supply voltage. For headphone applications, which do not need as much output power, you can connect the headphone between earth and one of the outputs, via an electrolytic coupling capacitor. You can make a stereo headphone amplifier in this way, using two TDS8551 ICs. The TDA8551 is housed in a DIP8 package. The SMD version is the TDA8551T, in an SO8 package.

Digital Volume Control

With this circuit you can make the amplifier volume control without having to use a potentiometer, but using a circuit with IC DS1669. For working voltage of the IC of this type was not 5 volts, but 4.5 VOLTS to 8 Volt, but used in this circuit at 5 V because it is more secure than the IC find that you are using exploded.

And the market is a lot of series this circuit of ICs such as:

• DS1669-10
• DS1669-50
• DS1669-100

Number after the hyphen that explains the resistance value of the IC, such as the DS1669-50 means that this ic 50K ohm resistance.

For the datasheet of this IC you can see below.

Pin Description IC DS1669

• RH - High Terminal of Potentiometer
• RW - Wiper Terminal of Potentiometer
• RL - Low Terminal of Potentiometer
• -V, +V - Voltage Inputs
• UC - Up Contact Input
• D - Digital Input
• DC - Down Contact Input

Standard resistance values IC DS1669

• DS1669-10 ~ 10 kΩ
• DS1669-50 ~ 50 kΩ
• DS1669-100 ~ 100 kΩ

How to make home made solar pannel

Solar Panel Build

Posted: October 3, 2011 | Author: ericbarch | Filed under: Projects |1 Comment Make sure to read both the Wind Turbine Build and the Solar Panel Build. Then watch The Tech Junkies Episode #9 that documents it all and puts them to the test!

Solar has really come down in price since the last time I looked. We wondered if we could start powering our shop off of solar. A good project would be to see if we can build a small scale solar array which would generate power back to the shop and keep it under $1/watt. This would have to include everything from the solar cells to getting usable power out the other end. So we started searching around.

Solar Cell Selection

We went to our favorite buying spot (eBay) and did some looking around to see how much we could find some solar cells for. We found that there are production error cells out there that have some blemishes or chipped edges and you can pick these up for dirt cheap….about 25 cents a watt. So we grabbed 2KG worth (they sell them by weight) which will allow us to make about a 500 watt array. The cells are 3.25″x6″ and are VERY FRAGILE! Who knew these things would break if you breathe on them too hard. They are 0.5 VDC with a maximum 3.6 Ampere output meaning they have a max output of 1.8 watts. Since some of them are chipped or blemished we need to figure we will get less than perfect output from them.

Solar Panel Size and Voltage Choice

We had 9 of the same old windows laying around the shop and they would work really good for about a 50 watt panel each. Wired together they should make a 450 watt array. Really any window panel size will do. Since we are making this on a budget, free windows will definitely help. Making common voltage solar panels helps in wiring them together so they are all working equally. You will lose some voltage from the diode that has to be installed on each panel, but shoot for 12, 18, 24, or 48 volt output panels or arrays.

Electrical Grid Tie Inverter Selection

What exactly is a Grid Tie Inverter and why is that what we want to use? It connects to your existing household AC outlet on on side, and your wind turbine on the other. It converts the DC wind power to an AC pure sine-wave matching the phase of the grid. Since the electricity is being generated on the house side of the power meter, the generated power will actually slow down your power meter or bring it to a stop. But if you are lucky enough to have an old dial turning style power meter AND are generating more power than you are using, it is possible to spin your electrical meter BACKWARDS! I didn’t believe it either until we tried it and it worked.
Grid tie inverters have come down in price and gotten pretty good recently. We expected to pay about 25 cents per watt in this part of the build. They are usually stackable too, which means as your system grows, you can just add another grid tie inverter and they will all just work in tandem.
This is the grid tie inverter we got. It was $138 (27.6 cents per watt) and again we sourced this from eBay.

Assembly and Testing

Here you can see we wired 11 cells in series for each row (5.5VDC). The cells vary voltage from top to bottom and vary current side to side. Meaning if you broke a cell in half 3×3 you would still measure full voltage and have half the amp output. We made 2 full rows, and a third row of cells we broke in half like we just mentioned. Edit: As pointed out by Hack a Day commenter Mark, we effectively limited the current of the entire panel by doing this. This can also lead to overheating in the half panels. At the time, our main concern was getting the voltage high enough for the inverter. For the next set of panels we will be using only full cells. So 3 rows of 5.5VDC = 16.5VDC, then minus the diode voltage drop and we should see around 15-17 Volts Output in operation. We plan on putting 3 panels in series and each series in parallel making a 45-51 Volt (or 48V standard) array.

It makes it easier if you pre-wire a lot of cells before you start. Here you can see we started making piles of them. It really goes quick and is pretty easy to get the hang of once you do a few. The trick is to get a soldering iron that can get hot enough to make it so you don’t have to spend a lot of time on any part of the panel for too long. It took us a few hours to build a 50 watt panel. That time involved will play a part in how big of a system you want to start with.

The cells get wired together easily by running “tabbing” wire down them after applying a flux pen. This make soldering to the solar cells painfully easy. Here you can see all 33 cells wired in series. With each full 3×6 cell theoretically capable of producing 1.8 watts and the halves at 0.9 watts this would be a maximum of 49.5 watts. We’ll round and call this a 50 watt panel.

Once all the cells are wired in place, we tape everything down and give it one last electrical test. This will temporarily hold it in place while we pour a two part polyester resin epoxy over it all to lock it in place.

Here is the epoxy sitting to harden up. When we made this we used old epoxy in cool temps and it came back to bite us. Ours peeled up and ended up taking so long to set up that it leaked through our masking tape and got under some of our panels. We figure we now need fresh epoxy and use about 1/10th of a gallon or less for this size panel. A little goes a long way and really this is just to give it a thin seal and lock everything in place.

Results and Thoughts

Here is the breakdown of our costs:
$125 Solar 3×6 cells creating 500 watts worth
$0 Windows
$50 Gallon of Epoxy
$25~$50 Tabbing wire and diodes
$138 Grid Tie Inverter
————-
So for roughly $375 we have built a Solar Array capable of producing 35-50 watts in it’s current state, with a maximum of 450 watts if we can get full sun. If we did this again we could get the price down even lower, but for about 75 cents per watt it would only take a few years for us to pay this system off.
The next step on this project is to finish the rest of the panels and tie them all in together and see some long term power generation to get an average for a year. Our first panel puts out about 35 watts in full sun, so we have some improvements to do for the next one.

Let the government pay for 30% of your alternative energy generation project!

As we were digging around with this project I want to make you aware that there are some really good government grants (AS IN FREE MONEY!!!) for those that take advantage of them. As always consult with a professional before deciding to spend any money and never take my word for it. But for what it is worth this website has a lot of good information about getting financial assistance in building alternative energy sources. Check out http://www.dsireusa.org/ to find out if your state has any local policies. As of the writing of this, as long as you START your build before the end of 2011 the Feds will pay for 30% of your project if it is under a commercial business. There are LOTS of grants and loan programs out there to help pay for the costs of installing these systems and now seems like a great time to do it. Earth will love you for it too.

Automatic Parking Light Switch Circuit

 This automatic park light switch with LDR automatically turn ON the light when the surrounding light dims to a preset level. The first circuit diagram is an NPN design intended for negative grounded chassis. The second diagram is the PNP version intended for a positive grounded chasis.

The dim level at which the circuit activates is set through the potentiometer P1.
The printed circuit board layout can be used for both the negative and positive polarity chassis. Take note that the transistors and different for each chassis type. The connectors labeled in the parts placement diagram have the following connections:
P = Power live of the car
C = Car chassis
B = Park light bulb

Automatic Park Light Switch Positive Ground

Automatic Park Light Switch Negative Ground

Parts Placement

Printed Circuit Board Layout

Hi-Fi AUDIO POWER AMPLIFIERS

Small stereo amplifier project for computer

you want will build a Small stereo amplifier project for computer. This projects is best for you. Before read detail of they we should read mono model on This is Super Small Power Amplifier BCL 1.2W by TDA7052. If you are seeking the circuit amplifies small-sized. I begs for to advise this circuit because tiny economize with the equipment is a little.
This is Super Small Power Amplifier BCL 1.2W by TDA7052. If you are seeking the circuit amplifies small-sized. I begs for to advise this circuit because tiny economize with the equipment is a little. And still can use force against large-sized get comfortablely ( I has tried already ) besides it still use volt power supply very wide be about 1.5V arrive at 15V as well. Regard as IC TDA7052 be worthwhile very much. For you who want to try build this circuit. I has model PCB give a friend tests to see with. Request have fun the circuit amplifies miniature please.

Circuit of Power Amplifier Super Small BCL 1.2W by IC TDA7052

PCB Power Amplifier Super Small BCL 1.2W by IC TDA7052

TDA 2050 Aamplifier

 
If you want to build hi-fi power amplifier the size about 30watt to 50Watt at good sound and build easy. I begs for to advise the circuit that builds with the integrated circuit. You wares IC TDA2050 then like very the circuit model class AB audio amplifier.
Thanks to its high power capability the TDA2050 is able to provide up to
35W true rms power into speaker 4 ohm load at THD =10%, VS =±18V, f = 1KHz and up to 32W into
8ohm load @THD = 10%, VS = 22V, f = 1KHz.Moreover, the TDA 2050 delivers typically 50W
music power into 4 ohm load over 1 sec at VS=22.5V, f = 1KHz
May take an interest want to try build already, try out this circuit use voltage Vcc +/- 25V.

Part
C1-0,47-22mF
C2-22mF
C3C4-100nF
C5-100(150)nF
R1R3-47kO
R2-1-3,3kO
R4-1-4,7oM/0,25W
Rt-4oM

PCB : 35W Hi-Fi AUDIO POWER AMPLIFIER by TDA2050

on PCB : 35W Hi-Fi AUDIO POWER AMPLIFIER by TDA2050

Mini 40 watt audio car amplifiers using HA13001

From this 20watt Integrated Amplifier project. Some people say that expensive and want the main amplifier only. I recommend this project, it had a budget of only 5$. and is the main amplifier. They have size of power to speaker is 40 watts and use voltage of power supply is 12 volts so can apply right in car. They use the HA13001-IC is key parts so small and build easily.
How This Circuit works
When see a circuit as Figure 1 Many people would doubt that. This circuit will be amplified up to 40 watts. (If as the RMS will is about 17.5 watts at load 4 ohms). You do not insult it because the many circuits that were contained in IC1-HA13001 of Hitachi there. Makes a few external devices, and the output of IC1 that connects to the loud speaker will be connected on the bridge circuit types. So causes the output has a high power there.

Figure 1 the circuits use IC-HA13001
We do not fear that the speaker will be damaged easily. because in IC1 has the Automatic Shut-Off circuit (ASO) that use to protect the speaker. Thus You need to carefree it. and this circuit will use the power supply range between about 12-18 volts for its’ source.
How to builds this projects
This simple project starting with make the PCB which has copper layout as figure 2 before. Then solder all components as figure 3. We can solder directly the IC1 onto PCB so should take special care.

Figure 2 The PCB layout

Figure 3 The components layout for PCB
The power supply that can use a DC adapter but must provide current over up 1 amperes. Otherwise, when you accelerate the more volume, the sound will be broken and Adapter will malfunction.
The application this projects
This amplifier project use to amplify from the various sound generator such as The iPad or mobile phone or notebook computer’s etc. Or Modified into the old car stereo that repair difficult. We changed the set to the amplifier.
The detial parts.
The electrolytic capacitors 16 volts
C1_________________1uF
C4, C5, C7, C8_______100uF
C6_________________47uF
C11________________2,200uF
The ceramic capacitors 50V
C2_________________0.001uF
C3, C9, C10__________0.1uF

IC1_number__________HA13001
¼ W + 5% Resistors
R1__________________1K
R2, R3_______________2.2 ohms
Speaker 20 W 4 ohms
Heat sink for IC1

High Current Voltage Regulation

Voltage regulators are available as easy to use three terminal integrated circuits - one terminal for the input voltage, one for the output voltage, and one for the ground (0V). The most commonly used are from the 78XX series - 7812 for 12 Volts, and 7805 for 5 Volts etc. Also of particular use for renewable energy generators are very efficient low dropout regulators such as the LM2940 series - LM2940CT-12 for 12 Volt etc.

One common shortfall of these common regulators is they are rated at just 1 Amp output current. It is usually possible to use them with higher currents, but a large heatsink and/or fan is essential. Regulators for higher currents than 1 Amp are available, but tend to be expensive, and still require good heatsinking.

Pictured above is a circuit from the Fairchild LM7812 datasheet. This uses a power transistor and a power resistor to take on some of the workload enabling higher currents to be regulated. With this set up, the power transistor and power resistor need heatsinking, and selecting the correct specification of transistor and resistor, and getting everything set up is not particularly easy.

One alternative is instead to parallel connect multiple three terminal regulators, with each regulator handling up to 1 Amp of current.

Parallel Connecting Mulitple Voltage Regulators

Voltage regulators such as the LM7812 cannot just be connected in parallel without additional circuitry. Each voltage regulator, though nominally rated at the same voltage, will in practice output a slightly different voltage - for example, three LM7812's could output 11.98, 12.01, and 12.06 respectively.

This tiny difference in voltage has the disastrous consequence of making the regulator with the lowest output voltage trying to carry all of the current. This will cause it's internal thermal protection to trigger (as the regulator overheats) effectively removing that regulator from the circuit and kicking off a chain reaction up through the remaining parallel-connected regulators.

The circuit shown above* (from the EDN article High-Current Supply uses Standard Three-terminal Regulator) has two LM7812 voltage regulators connected in parallel for a maximum total output current of 2 Amps - double the rated current of one LM7812.
* Diodes D1, D2, and D should be 1N4007 according to the EDN article, but common 1N4001 diodes will be fine as they are rated up to 50V which is more than enough. The capacitors are supposed to be C=47,000uF, C1 and C2 are 4,700uF, but as a 47,000uF capactitor is expensive and physically very large we tested this regulator using a 4,700uF for C, and 1,000uF for C1 and C2 and had no problems.

An even simpler way to parallel connect multiple voltage regulators together is to add very low (below 1 Ohm) ballast/equalising resistors in series with the regulator outputs. Doing so should make the regulators share current equally and therefore operate together without problems. It is worth noting however that this approach to load balancing makes the voltage regulation a bit less accurate.

An example of this simplistic approach in use can be seen in the above experimental 12V 6A power supply* in which six LM7812 regulators were connected in parallel with 0.25 Ohm load balancing resistors (made up of four 1 Ohm resistors in parallel) connected in series with the output from each 7812 regulator. The schematic shows the key elements in this 6 Amp 12 Volt regulator.
* The original circuit diagram was published on the Wroclaw University of Technology website back when we first published this article in 2006/7. Unfortunately that article is no longer online.

High Current Variable Voltage Regulation

Where you need to have a user variable voltage output, the LM317 is an excellent adjustable voltage regulator to use. The output voltage is adjusted using a couple of resistors, and one of these resistors can be replaced with a potentiometer to give an adjustable output.

While the LM317T for example is limited to a continuous output of 1-1.5A subject to sufficient heatsinking, one or more power transistors can be added as shown above to make an adjustable high current power supply. Click here for full details: LM317 Adjustable Power Supply.

Comment on this Article

If you have any comments on this article, please email them to neil@reuk.co.uk.

Hello from Kentucky USA! In regard to this page, I have drawn up a couple of 78xx high current circuits you might like to consider. I've used them for a 30amp power supply with a 7815 regulator. REUK Added Info: The MJE3055 is an NPN silicon power transistor rated at up to 60V, up to 75 Watts, and up to 10 Amps. Click here to view the MJE3055 Datasheet for more information. If you are unable to find the MJE3055, any NPN power transistor with a similar rating can be used instead. Click here to view a selection of NPN power transistors. I have since switched to using the better LM723 regulator so that I can adjust the voltage and it is far more reliable than the 78xx. I have used the LM723 for a 105amp supply. REUK Added Info:The LM723 is a voltage regulator rated for outputs of 150mA at an adjustable voltage from 2V to 37V. By adding transistors as shown in the schematics above high output currents at the regulated voltage can be output. Click here to view the LM723 datasheet. The LM723 is available in the UK from around 30 pence. Click here to buy an LM723 now. I've learned a few things on your site so I thought I'd pass along a little in return. Ken Weaver, 17th August 2009 The benefit of this first schematic is that the output is actually regulated; the PNP is fully in the feedback loop. However in Ken's circuit, the bases of the 3055 are regulated, but not the emitters, where the output is taken. Thus for every current ratio of 2.7 the voltage drops by 25mV. Nick, 10th July 2012

rrent.

Adjustable Power Supply with Charger

Circuit :

Notes:

This power supply has adjustable and charger output. The charger circuit can be use for cellular phone. The adjustable output serves as multipurpose power supply. It can handle a 1 ampere current. The 317 must have a heat sink.

PCB Layout:

Parts List:

Semiconductor:
LM 317 - 1pc
LED - 1pc
1N 4001 - 8pcs

Capacitors:
25V/470uF - 1pc
25V/10 uF - 1pc

Resistors:
1k, 1/2W - 1pc
220R, 1/2W - 1pc
5kR Potentiometer - 1pc

Others:
1Ampere, Multi-tap Transformer - 1pc
AC Chord - 1pc
Casing - 1pc
#22 Stranded Wire - 3m
Heatsink for TO220

Nicad Battery Charger

Description:

A basic nicad battery charger using a single medium power transistor.

Notes:

This simple charger uses a single transistor as a constant current source. The voltage across the pair of 1N4148 diodes biases the base of the BD140 medium power transistor. The base-emitter voltage of the transistor and the forward voltage drop across the diodes are relatively stable. The charging current is approximately 15mA or 45mA with the switch closed. This suits most 1.5V and 9V rechargeable batteries. The transformer should have a secondary rating of 12V ac at 0.5amp, the primary should be 220/240volts for Europe or 120volts ac for North America.

Warning:

Please take care with this circuit. Use a voltmeter to observe correct polarity. Nicads can explode if short circuited or connected with the wrong polarity.

2WATTS FM TRANSMITTER

USE DIPOLE ANTENNA FOR MAXIMUM RANGE (COULD BE UP TO 10 KM IN GOOD WEATHER). TUNE BETWEEN 88-108 MHz WITH C5. BB-204 COULD BE REPLACED WITH CONVENTIONAL LED (BIG) WITH REVERSE BIAS (NO LIGHT GIVEN IN CORRECT POLARITY). 9V POWER FOR 2KM WITH GOOD SOUND QUALITY AND GRADUALLY UP TO 18V FOR 10 KM RANGE WITH POOR QUALITY OF SOUND.  BEST OF LUCK.

High Voltage Converter: 90V From 1.5V

The circuit shows one way of obtaining a voltage of 90V from a 1.5V battery supply. The LT1073 switching regulator from Linear Technology (http://www.linear-tech.com) operates in boost mode and can work with an input voltage as low as 1.0 V. The switching transistor, which is hidden behind connections SW1 and SW2, briefly takes one end of choke L1 to ground. A magnetic field builds up in the choke, which collapses when the transistor stops conducting: this produces a current in diode D1 which charges C3. The diode cascade comprising D1, D2, D3, C2, C3 and C4 multiplies the output voltage of the regulator by four, the pumping of C2 causing the voltage developed across C4 via C3, D2 and D3 to rise.

Finally, the regulator control loop is closed via the potential divider (10 MΩ and 24 kΩ). These resistors should be 1 % tolerance metal film types. With the given component values, fast diodes with a reverse voltage of 200 V (for example type MUR120 from On Semiconductor http://www.onsemi.com) and a choke such as the Coilcraft DO1608C-154 (http://www.coilcraft.com) an output voltage of 90 V will be obtained. The output of the circuit can deliver a few milliamps of current.

Build-very-low-cost-FM-transmitter

1. No. of stage: 4

2. Frequency of operation: About 100MHz

3. Antenna type: Folded 300 ohms dipole.

4. Range obtained in free space: Up to 4km with dipole antenna 30 feet above ground level. More   range with yagi antenna.

Brief Description:

The transmitter is built on a Printed Circuit Board. This board uses track inductor for L1, L2 and part of L3. The section built around Q1 is the oscillator section. Oscillation frequency is determined by L1, C4 & C5 which forms the tank. Actually C5 is the feedback capacitor. This is required to sustain oscillation. This also influence the operation of tank formed by L1 & C4. Modulation is directly applied to the base of Q1 via C2. A microphone is connected here to serve this purpose. You can alternately feed direct audio here after disconnecting the microphone biasing resistor R1. Q2, Q3 & Q4 gradually raises the output power up to the desired level.

As most of the inductors are PCB etched, there is practically very little frequency drift provided you use a highly regulated and ripple free power supply.

RF output from the transmitter is taken from the junction of C11 & C12. This is unbalanced output of around 75 ohms impedance. But a folded dipole is a balanced type antenna of around 300 ohms impedance. So we need to use a 'BALanced to UNbalanced transformer' or 'BALUN'. A 1:4 type BALUN is employed here for this purpose. Antenna connection is taken from this BALUN via a 300 ohms flat parallel feeder cable commonly used in television to receive terrestrial broadcast. No coaxia is used to feed antenna. This saves cost. Also a parallel feeder cable provides much less signal loss compared to a coaxial.

Design of BALUN
The BALUN is made using a two-hole binocular ferrite bead as shown above. You need to use parallel insulated twin wire to construct this. This wire is commonly used to wind TV BALUN transformer. If you want to get rid of this, then buy a ready-made TV BALUN that is generally used at the back of your television set for interfacing with feeder wire.  

 
If you prefer to build this yourself, the circuit diagram is given above. You need to carefully construct it keeping in mind about the 'sense' & 'direction' of turns. See there are four coils. Two coils in the upper section, which are red and blue, required to be wound on left side of the BALUN and the remaining two (blue & red) in the lower half to be wound on right side. Connection marked 'A' and 'B' at the left side of the circuit is reqired to be connected to the PCB at the shown point. As dipole antenna is balanced type, so you need not to worry about its connection.

 

PCB design details
The transmitter is built on a single sided PCB. As mentioned earlier, this PCB has a number of etched inductors. For this reason, you need to very carefully construct the PCB as mentioned below.

 

In the copper side view, you can see that there are three track etched inductors that resembles 'RCL' Every corner and track width/length are calculated and then they are drawn so that each 'RCL' section becomes an inductor of required value. Never play with this; otherwise, optimum result could not be achieved.

You need to use a laser printer or a high quality printer to get a printout of the drawings. First, save the picture to disk. Now try to print it from such a software which permits you to control print size. 'Paint Shop Pro' is such a software. Of course you can use any other software. Print the drawing so that copper side drawing is exactly 59mm X 59mm. Few trial will give you the perfect print. Now construct the PCB using 'Photo-etching' method so that all the tracks becomes exactly same as you are now seeing. Now drill the PCB carefully. The PCB is now ready to populate.

Start population according to the component mounting plan. You can also get a true size copy of this plan printed and glued to the PCB. This will help you work fast.Part of L3 is required to be constructed. This is described in parts list.

Please note that in the picture of the transmitter kit, capacitor C1 & C10 are not mounted by mistake and the kit is filmed. Please add these two capacitors. Try to keep all component leads as short as possible.

Now you need to design the dipole antenna to use with the kit.

N.B: Believe it or not, a 2N2369 from Philips, used in the final power amplifier section, can give this much of range. 

Detailed Parts List:

RESISTORS

R1 - 22K

R2 - 100K

R3, R7, R9 - 1K

R4, R8 - 100E

R5 - 390E

R6 - 330E

R10 - 15E

R11 - 10K

CAPACITORS

C1, C3, C10 - 1n

C2 - 100n

C4,C8,C9 - 47pF

C5, C11 - 10pF

C6 - 100uF/25V Electrolytic

C7 - 100pF

C12 - 3pF

TRANSISTORS

Q1, Q2, Q3 - BC548

Q4 - PN2369 (Plastic casing) or 2N2369 (Metal casing)

MISC.

L3 - 7 turns, 22SWG wire, 3mm ID, Close wound, Air core.

Two hole binocular BALUN core, BALUN wire, 300 ohms TV feeder wire,

JP1 to JP5 - All jumper wires.

This completes the Project. Please mail me with your feedback. It will really encourage me to give you more & more project like this.

Battery charge controller

A charge controller circuit for battery makes you hassle-free by not bothering about switching the charger with different battery levels, the main advantages being improved life and low current consumption as it switches off the charger when battery full charged. So far we have published a simple battery charge controller circuit using 555 IC where many of our readers commented that it was difficult for them to set the threshold levels and also it seemed like it was harder to analyze working of the same.
For the above reasons, I have decided to introduce another one where you could find it easier to set the threshold levels. Furthermore, this charge controller design makes it easier for debugging. The main component of this circuit is a LM324 comparator IC which has four inbuilt comparators inside; here we are making use of only one. You can use any other comparator ICs instead of this one, like LM358, LM317, LM339 etc. I have used lm324 here owing to its high availability. For basic electronics learners see what is a comparator.
Read: Battery charging circuit with battery level indicator
As the threshold levels to turn ON and turn OFF the charger are different (hysteresis), it helps to avoid oscillation problems of the relay due to leakage current of battery. The threshold levels can be set by varying the potentiometer. As we are switching the charger with the help of relays, you can connect any capacity battery. High current transformers are recommended when using higher capacity batteries to decrease the charging time. For small capacity batteries you should use a series resistance to limit the charging current and that’s not necessary for higher capacity batteries.
This charging controller circuit can be applied with any system that makes use of rechargeable batteries like emergency, UPS, inverters, telephone receivers etc. Here we have used LEDs to indicate the charging status. Also at the bottom I have uploaded a video demonstration to guarantee you that this charge controller schematic is 100% working.

Battery charge controller circuit diagram

Components Required:

1. LM324 IC
2. Zener diode 5.1V
3. Bridge IC/1N4007X4
4. Transistor BC548X2
5. Led Green
6. Capacitor 1000uF
7. Resistor 1KX4, 100K
8. Pot 50K/47K
9. Relay 12V/10A
10. Transformer 0-15V/2A

Working:

• Step down transformer steps down the line voltage to 15 volts and bridge rectifier does the AC to DC conversion process (rectification), it’s followed by the capacitor filter which removes AC ripples.

• The power supply for the working of charger circuit is given from the battery (as it should always be monitoring the battery voltage level even when the mains supply is disconnected).

• The non-inverting terminal of the comparator is connected to a zener diode and 1k resistor which are used to make a reference voltage of 5.1 volt, and its inverting terminal is used to monitor the battery level.

• Usage of zener diode instead of resistors makes sure that the reference value is independent of battery level and temperature variances.

• In fact the comparison is not between reference voltage and the actual battery voltage, but between a proportional value of battery level and reference value. This proportional value is achieved by using a potentiometer.

• If the battery level is below the Lower Threshold Point (say LTP), then the reference voltage becomes higher than the proportional battery value. Thus output of comparator becomes positive.

• Then the transistor is switched ON (as output of comparator is connected to the base of transistor BC548 through a 1k resistor) followed by the relay. I have used a freewheeling diode along with the relay to de-energize the inductor.

See:Working of relay with animation

• And when the comparison goes reverse, output of comparator is low and transistors are OFF resulting in the disconnection of supply.

• Output of comparator is also connected to another BC548 through a 1k resistor which make hysteresis. That means when the charger is ON, transistor is ON and it makes a 100k resistor parallel with the respective voltage divider, then the drop across the divider will again decrease increasing the charging level.

• Upper Threshold Point (voltage level when charger is switched OFF) can be set by varying the potentiometer.

• The difference between UTP and LTP (hysteresis) can be varied by changing the 100k resistor, decreasing the resistance increases the hysteresis and vice versa.

• A 8.2ohm 10 watt resistor connected in series with the circuit helps to limit the charging current. It’s not required for higher capacity batteries as the charging time will increase.