This power supply is meant as an auxiliary or as a permanent power supply for all common circuits based on a stabilized DC voltage between 3 and 30V provided that the consumption does not exceed 3A. Of course this power supply unit can also be used for other purposes. Be replacing the trimmer by a potentiometer, it may even be used as an adjustable power supply unit. A good quality heatsink must be used.
Picture of project:
Figure 1. 3 TO 30 Volt 3 Ampere DC Power Supply
Circuit diagram:
Figure 2. 3 TO 30 Volt 3 Ampere DC Power Supply Circuit Diagram
Parts list:- R1 = 8.2K
- R2 = 2.2K
- R3 = 680R
- R4 = 1K
- R5 = 82K
- R6 = 0.18R/5W
- C1 = 470p
- C2 = 100nF-63V
- C3 = 100nF-63V
- C4 = 100uF-63V
- C5 = 10KuF-60V
- D1-D6 = 6.6A
- Q1 = MJ3001 (Darligton)
- IC1 = UA723D
- Overload protected
- Short-circuit stable
- Output current: max. 3A
- Output ripple voltage: 0.5mV
- Output voltage: adjustable from 3 to 30V, stabilized
- Input voltage: 9 to 30V AC (depending on the desired output voltage)
- Depending on the transformer used, one may chose one of two housings
- If a metal housing is used, it must be earthed for security purposes.
- Make sure the cooling body does not touch the housing. This might cause a short circuit.
- When mounting a toroidal transformer, it must be seen to that the fixation bolt does not touch the cover. This might cause the burning of the transformer
- If the circuit is to be integrated into another housing, it must be provided with ventilation holes (one may make these holes oneself), necessary for the release of the heat developed.
- Connect a voltage meter to the points ‘GND’ and ‘+OUT’ and adjust ‘RV1’ until the desired output voltage is reached.
- Apply some thermo-conducting pasta to the bottom side of the transistor and mount it on the heatsink.
- If you need 3-8 volt then R2 will be 5.6K
- If you need more than 8 volts then the R2 will be 2.2K
- Suitable transformer 30vAC at 120VA
It is so a nice project that here is made. It is just a pity, it can not go down to 0 Volt out.
ReplyDeleteTry changing the circuit this way:
Divide Vref down to 5 Volt. Connect + input to that. Divide Vref down to 6 Volt to top of a voltage adjust pot of some 2.200 Ohm. From wiper of pot to - input, use a resistor of 2000 Ohm. From output voltage and return to - input, a resistor of 10000 Ohm. Use a standart, or 3 - 4 2N3055 as high current elements. Use a PNP as driver for them. Use the collector of the output transistor in the uA723 instead, and let the emitter of that transistor be connected to 0 Volt through the zenerdiode.