Simple and cheap, the circuit built based on well-known IC regulator LM317 with current booster of power transistor 2N3782. Don’t forget to add heatsink especially for power transistor 2N3782.

A switching power supply is a type of power supply that uses electronic switches to control the flow of electrical energy. Unlike linear power supplies, which regulate the output voltage by dissipating excess energy as heat, switching power supplies are more efficient because they switch the input voltage on and off at a high frequency.

Switching power supplies are widely used in electronic devices, computers, telecommunications equipment, LED lighting, and other applications where efficiency, size, and weight are critical considerations. However, they can introduce electrical noise, and careful design is required to minimize electromagnetic interference (EMI).

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Parts list:
R1, R2 = 4.7 K
C1, C2 = 4700 uF / 16V
C3 = 47,000 uF / 35V
D1,D2, D3 = 1N5401 ( 3 Amp Diodes )
D4 & D5 – Light Emitting Diodes (LED)**
IC1, IC2 – 78xx series regulator IC ( 7805 for 5V, 7812 for 12V etc.)

Nothing critical here. Detail instruction: go to this page

My Notes:

• The original circuit source said that the diode is 1N4003 (3A diodes). That’s is a mistake, the correct diodes should be 1N5401. 1N4003 is 1A diode with higher voltage.
• Schottky diodes is recommended.

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The circuit details are based on european standards: 120E, 150E, etc. The ‘E’ just stands for Ohms so 120 ohm, 150 ohm. The original circuit specified the HEF type of CMOS IC’s that are not readily on the market in most of worldwide country. So just get any other kind of CMOS chip like the MC4011, MC4020, MC4047 from Motorola. Any other type will work fine too. The BC548B is replaceble by a NTE123AP (NOTE: ensure it’s the ‘AP’ type, the typical NTE123A is a total different transistor), ECG123AP, and also the 2N3904 will be work. Watch for the proper pin locations because the BCE may be reversed with this european type. The LM317T is a TO-220 type and replaceble with a ECG956 or NTE956. The LM339N could be changed using a ECG834 or NTE834

Even though this battery charger circuit looks pretty impressive and perhaps a bit complex, it’s actually not difficult to understand. The circuit needs to be hooked-up to a DC supply voltage of between 16.5 and max 17.5 volt, otherwise the CMOS IC’s will go defective. Simply because I didn’t feel like to build a seperate power supply for this circuit, I connected it to my fully variable bench top power supply.

To start with, we connect a ‘to-be-charged’ 9-volt nicad battery to the suitable connections. Then hook it up to the power supply. Upon connection the 1nF capacitor starts up the two RS Flip-Flops formed by IC1a, IC1b, IC1c, IC1d, and pulls pins 3 and 10 ‘high’ and pins 4 and 11 ‘low’. The clock pulses are created by the free-running multivibrator IC4. IC4’s frequency is determined by the 10uF capacitors, the 220K resistor and the 100K trimpot. The clock runs continuesly but the counter behind, IC5, is not counting however because pin 11 (the master-reset) is kept high. When the ‘START’ button is pressed, output pin 4 from IC1a goes high and biases TR4, which is made visible by the Red LED (D9) which remains lit. The NiCad is now becoming discharged via this transistor and also the 100 ohm resistor.The 10K trimpot (at the right of the diagram) is adjusted in such a way that when the battery voltage dips below 7 volt, the output of IC3 goes LOW and the output pin 11 of IC1a HIGH. At hte same time the output pin 10 of IC1d goes LOW, and also the red LED turns off.

Because output pin 11 went HIGH the green LED (D8) lights up and at the exact same time the voltage level rises causing the battery to be charged. The charge-current is determined by the 120 ohm, 150 ohm, and the trimpot of 1K, at the right side of IC2. Really we could have used 1 resistor, but the output voltage of different brands for IC2 may differ, by about 1.25 volt.

Simply because the charging present is devided by value of the resistors, with the trimpot the current could be adjusted to the correct value of your own 9-volt NiCad. (In my case, the battery is a 140 mA type, so the charge present should be adjusted for 14 mA (c/0.1).

At the exact same time the LOW of output pin 10 from IC1d starts the counter of the clock. On pin 9 of IC5 appear pulses which light up the red LED. This is implemented for two factors, the clock-frequency can, with the 100K trimpot, be adjusted to the correct value; the red LED has to come ON for 6.59 seconds and for the same duration going OFF and except for that fact the green LED, who indicates the charge current, can be checked if the total charge-time is correct.When the counter has reached 8192 pulses ( x 6.59 = 53985.28 sec = 14.99 hours) the output pin 3 of IC5 goes high again, transistor Tr1 activates and resets the two flip-flops to the start position.

The charging process stops and goes over to trickle charge via the 10K resistor and the D2 diode and keeps the battery topped-up.The adjustments of the project are truly extremely simple and nothing to be concerned about. Turn the walker of the 10K pot in the direction of the 12K resistor, ground connection point of 10K resistor/diode D2, like the adjustment pin of IC2, apply a voltage of 7-volt to the battery connection terminals, switch the power ON and slowly turn the pot backward until the greeen LED starts to light up. Switch OFF the power and take away the connections you created to make the adjustment.Insert an amp-meter between the battery and also the output connection and again switch the power ON. The battery will, in case it is not totally empty, totally discharged (to a secure level) and as soon as the 7 volt margin is reached goes over to the charge cycle. The charge present is at this time adjusted via the 1K trimpot (which is connected in series with the 150 Ohm resistor and in parallel with the 120 ohm resistor) accurately to the desired value.

Addendum: It’s strongly suggested to include little 100nF ceramic capacitors over the power supply lines feeding Every CMOS IC to keep feasible interference to a negliable value.

The post Automatic 9V Battery Charger appeared first on Circuit Schematic Diagram.

When power supply is restored, the lamp or the alarm is switched-off. A switch provides a “latch-up” function, in order to extend lamp or alarm operation even when power is restored.

This circuit is permanently plugged into a mains socket and NI-CD batteries are trickle-charged. When a power outage occurs, the lamp automatically illuminates. Instead of illuminating a lamp, an alarm sounder can be chosen.

Components List:

R1____________220K   1/4W Resistor
R2____________470R   1/2W Resistor
R3____________390R   1/4W Resistor
R4______________1K5  1/4W Resistor
R5______________1R   1/4W Resistor
R6_____________10K   1/4W Resistor
R7____________330K   1/4W Resistor
R8____________470R   1/4W Resistor
R9____________100R   1/4W Resistor

C1____________330nF  400V Polyester Capacitor
C2_____________10uF   63V Electrolytic Capacitor
C3____________100nF   63V Polyester Capacitor
C4_____________10nF   63V Polyester Capacitor

D1-D5________1N4007 1000V 1A Diodes
D6______________LED  Green (any shape)
D7___________1N4148   75V 150mA Diode

Q1,Q3,Q4______BC547   45V 100mA NPN Transistors
Q2,Q5_________BC327   45V 800mA PNP Transistors

SW1,SW2________SPST Switches
SW3____________SPDT Switch

LP1____________2.2V or 2.5V 250-300mA Torch Lamp Bulb
SPKR___________8 Ohm Loudspeaker
B1_____________2.5V Battery (two AA NI-CD rechargeable cells wired in series)
PL1____________Male Mains plug

Circuits Works:
Mains voltage is reduced to about 12V DC at C2’s terminals, by means of the reactance of C1 and the diode bridge (D1-D4). This avoids the use of a mains transformer.

Trickle-charging current for the battery B1 is provided by the series resistor R3, D5 and the green LED D6 that also monitors the presence of mains supply and correct battery charging.

Q2 & Q3 form a self-latching pair that start operating when a power outage occurs. In this case, Q1 biasing becomes positive, so this transistor turns on the self latching pair.

If SW3 is set as shown in the circuit diagram, the lamp illuminates via SW2, which is normally closed; if set the other way, a square wave audio frequency generator formed by Q4, Q5 and related components is activated, driving the loudspeaker.

If SW1 is left open, when mains supply is restored the lamp or the alarm continue to operate. They can be disabled by opening the main on-off switch SW2.

If SW1 is closed, restoration of the mains supply terminates lamp or alarm operation, by applying a positive bias to the Base of Q2.

Notes: Close SW2 after the circuit is plugged.

source: redcircuits.com

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Components List:
R1 = 18K Ohm
R2 = 240 Ohm
R3 = 8.2K Ohm
R4 = 3K Ohm
R5 = 10 Ohm
M1 = Panel Meter (Anyone will work)

Design Issues to consider:
It’s possible you have test with the values of R3 and R4 to have a precise reading from the meter. Every meter is different, so a little bit of experiencing using the resistor values is needed. Experiment by using a variable resistor instead of R3 & R4 to get a value of resistance that works.

The post 1.5V and 9V Battery Tester appeared first on Circuit Schematic Diagram.

The lamp L1 will be light brightly and the LED will be out when the battery is low and battery charging in progress, but the LED is very bright and the lamp L1 dim when the battery is almost ready to use (charge complete). L1 must be a bulb lamp rated for the current you want (usually the battery capacity divided by 10).

The diode D1 should be at least 1 A, and Z1 is a zener diode 1 W with a voltage determined by the fill-charge battery voltage minus 1.5 V. When the battery is fully charged, the circulatory flow around the battery capacity divided by 100 mA.

The supply voltage can be from 12V power supply or from 12V lead acid battery from your car via cigarette lighter socket.

The post NiCAD Battery Charger with Current and Voltage Limiting appeared first on Circuit Schematic Diagram.

120W Power Amplifier Part List

Transistors

• 2N3055 (substitution: MJ15003 or 2N3772) : 2
• MJ2955 (substitution: MJ15004 or 2N3771) : 2
• TIP42 : 2
• TIP41 : 1
• 2SC2229 or 2SC2230 or C1573 : 2
• A1015 or A872 or A733 : 2

Capacitors

• 100uF/50V electrolytic capacitor: 2
• 470nF (474) nonpolar polyester capacitor: 1
• 100pF (101) nonpolar ceramic capacitor : 2
• 470pF (471) nonpolar ceramic capacitor : 2
• 10pF nonpolar ceramic capacitor : 2
• 100nF (104) 100V nonpolar polyester capacitor : 2

Resistors

• 0.33 Ω (5W) : 4
• 10 Ω to (1W) – brown, black, black : 1
• 100 Ω (1W) – brown, black, brown : 2
• 33 Ω (1/4W) – orange, orange, black : 1
• 150 Ω (1/4W) – brown, green, brown : 3
• 10KΩ (1/4W) – brown, black, orange : 1
• 1KΩ (1/4W) – brown, black, red : 1
• 4.7KΩ (1W) – yellow, violet, red : 1
• 68KΩ (1/4W) – blue, gray, orange : 1
• 56KΩ (1/4W) – green, blue, orange : 1
• 33KΩ (1/4W) – orange, orange, orange : 1
• 3.3KΩ (1/4W) – orange, orange, red : 2

Diodes

• 3A Diode 1N5404 : 2
• 1A Diode 1N4007 : 3
• Zener diodes between 20 and 24 volts : 1

Others

• 3A fuse
• small 3-pin (GP) connector
• large 6-pin connector (Molex)
• aluminum heatsink
• potentiometer of 20K if you want to add volume control

120W Power Amplifier PCB Layout Design

Bottom PCB Layout (Copper)

Top PCB Layout and Component Placement

How to mount the transistors to the aluminium heatsink, see below image:

The points are: prevent circuit shortage, use proper isolator and use thermal compound for maximum heat spreading to the heatsink. Use mica between the transistor and the heatsink.

Power Supply Circuit for 120W Power Amplifier

Power Supply Bottom PCB Layout

Power Supply Top PCB Design

Power Supply Part List

• Transformer for the mono amplifier should be 35 + 35 volts AC with a minimum of 3 amps. If the stereo channel, the amperage should be doubled.
• Capacitors of 4700 uF/63V: 4
• Diode bridge (rectifier) ​​of 15 Amps: 1

120W Power Amplifier Wiring Connection

This is how to connect the amplifier module to the speaker, power supply and audio input. And connect the power supply module to the transformer.

The post 120W Power Amplifier + Power Supply appeared first on Circuit Schematic Diagram.

Components List:

Resistor: 1 K Ohm, 68 Ohm, 2 K Ohm, Potensiometer 10K Ohm
Diode: IN4001, 2x Zener IN752
Transistor: 2N2219, 2N2222

This NiCAD battery charger circuit charges the battery at 75 mA until the battery is charged, then it reduces the current to a trickle rate. It will fully recharge a dead/unpowered battery in 4 hours and the battery can be left in the charger indefinitely. To set the shut off point, connect a 270 ohm / 2 Watt resistor across the charge terminals and adjust the potensiometer for 15.5V across the resistor.

The input voltage for this battery charger circuit is 24VDC, you may use a general purpose power supply or 24V lead acid battery from your car.

The post 200mA/Hour – 12V NiCAD Battery Charger appeared first on Circuit Schematic Diagram.

Powered with solar panel, the circuit will give you 5V pure regulated DC voltage. This solar cell power supply circuit is made up of an oscillator transistor as well as a regulator transistor. The solar panel charges the battery when sunlight is bright enough to generate a voltage above 1.9v. A diode is necessary between the panel and also the battery as it leaks about 1mA from the battery when it really is not illuminated. The regulator transistor is intended to limit the output voltage to 5v. This voltage will likely be maintained over the capability of the circuit, which is about 10mA.

The oscillator transistor should be a high-current sort as is is turned on for an extremely limited time period to saturate the core of the transformer. This energy is then released as a high-voltage pulse. These pulses are then passed to the electrolytic and appear as a 5v supply, having a capability of about 10mA. If the electric electric current is increased to 15mA, the voltage drops to about 4v.

The transformer is wired to ensure that it gives POSITIVE feedback. The transistor turns on via the 1k resistor and this produces expanding flux inside the core. The flux cuts the turns of the secondary winding and produces a voltage that ADDS to the turn on voltage and also the transistor is turned on A lot more. The transistor gets totally turned ON as well as the electric current via the main becomes a maximum. The core becomes saturated and though the flux is really a maximum, it really is not expanding flux and therefore the secondary produces no voltage (only the voltage and electric current supplied by the battery).

The voltage and electric current into the base of the transistor is decreased, and this cuts down the electric current via the main. The flux now begins to collapse and this produces a voltage in the secondary of an opposite polarity. This turns the transistor OFF and also the magnetic flux collapses shortly and produces a high voltage. This voltage is passed via the diode and charges the electrolytic. The circuit operates at approx 50kHz as well as the pulses shortly charge the electrolytic.

The 15k resistor has a 3k3 “trimmer” resistor to allow you to adjust the output to specifically 5v or slightly above 5v. Microcontrollers will operate up to 5.5v but some will freeze at 5.6v, so be careful. The output voltage is monitored at the join of the 15k resistor (and 3k3) as well as the 2k2 resistor. The voltage at this point is precisely 0.63v (630mV) and at this voltage, the regulator transistor turns ON and robs the oscillator transistor with “turn-on” voltage.

When a load is placed on the output of the circuit, the voltage across the electrolytic drops as well as the regulator turns off slightly. This permits the oscillator transistor to operate “harder” and send pulses of energy to the electrolytic to charge it. If the load is removed, the electric current consumption of the circuit is about 3.5ms. This may be the quiescent current in the circuit.

The output electric current is limited as every mA needs about 5mA from the battery. On 15mA output, the current needed from the battery is about 75mA. That is why we need a high-current capability transistor for the oscillator. A BC 547 transistor won’t function, as it really is not capable of passing a high electric current.

The solar panel will deliver about 10 – 15mA on bright sunlight, so any load on the output should be as small as possible. An example is information logging, exactly where the micro is active for short periods of time, then goes into “sleep” mode.

5V Regulated Solar Cell Power Supply circuit source: talkingelectronics.com

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This is the circuit diagram of adjustable symmetric 1 to 24VDC, 1A Power Supply. This power supply give dual output positive and negatif output, you can adjust both positif and negative output (+1 to +24VDC and -1 to -24VDC). This kind of power supply also known as dual polarity power supply or splitted power supply which give positive anf negatif output.

This power supply can be used for universal usage, which required not more than 1A DC current. Please take a note that you should adjust the output voltage using general multimeter or DC voltmeter before use this power supply to protect the supplied devices.

Circuit Features:

• Low cost universal symmetric power supply
• Just add a suitable transformer and a heatsink
• Ideal for e.g. op-amp applications, amplifiers, …
• Trimmers can be replaced by potmeters to allow continuous adjustment of output voltage
• LED output indicators

Circuit Specifications:

• Positive and negative output adjustable between 1.2 and 24VDC
• Output current: up to 2 x 1A continuous (with suitable heatsink)
• Max. input voltage: 2 x 24VAC
• Very good line and load regulation
• Low ripple
• Short circuit protection
• Thermal protection

Circuit Manual of Adjustable Symmetric 1 to 24VDC, 1A Power Supply:

Adjustable Symmetrical Power Supply

1 file(s) 1.45 MB

Download Circuit Manual

Kit Version:
This circuit available in kit version by valleman, you may purchase this kit online.

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