Power supply circuit » 2N3055 power supply http://apowersupply.com Sat, 19 May 2012 07:51:49 +0000 en hourly 1 http://wordpress.org/?v=3.1 3 to 24V Variable Power Supply http://apowersupply.com/3-to-24v-variable-power-supply-387.html http://apowersupply.com/3-to-24v-variable-power-supply-387.html#comments Sun, 22 Apr 2012 21:59:16 +0000 aPowerSupply.com http://apowersupply.com/?p=387 This 3 to 24 volt variable-regulated power supply can be adjusted from 3 to 25 volts and is current limited to 2 amps as shown, but may be increased to 3 amps or more by selecting a smaller current sense resistor (0.3 ohm). The 2N3055 and 2N3053 transistors should be mounted on suitable heat sinks and the current sense resistor should be rated at 3 watts or more.

Voltage regulation is controlled by 1/2 of a 1558 or 1458 op-amp. The 1458 may be substituted in the circuit below, but it is recommended the supply voltage to pin 8 be limited to 30 VDC, which can be accomplished by adding a 6.2 volt zener or 5.1 K resistor in series with pin 8. The maximum DC supply voltage for the 1458 and 1558 is 36 and 44 respectively. The power transformer should be capable of the desired current while maintaining an input voltage at least 4 volts higher than the desired output, but not exceeding the maximum supply voltage of the op-amp under minimal load conditions.

The power transformer shown is a center tapped 25.2 volt AC / 2 amp unit that will provide regulated outputs of 24 volts at 0.7 amps, 15 volts at 2 amps, or 6 volts at 3 amps. The 3 amp output is obtained using the center tap of the transformer with the switch in the 18 volt position. All components should be available at Radio Shack with the exception of the 1558 op-amp.

Variable Power Supply Circuit Diagram

variable power supply

]]> http://apowersupply.com/3-to-24v-variable-power-supply-387.html/feed/ 0 Variable power supply http://apowersupply.com/2n3055-variable-power-supply-164.html http://apowersupply.com/2n3055-variable-power-supply-164.html#comments Sun, 05 Feb 2012 16:13:44 +0000 aPowerSupply.com http://apowersupply.com/?p=164 This simple variable power supply circuit has a low production cost and delivers an output voltage between 1,5 V and 15 V with a 500 mA maximum current. Its stabilization is better than 2% if the current consumption do not exceed 350 mA. The variation of the power supply voltage can be made with a potentiometer and when overloading occurs a buzzer sounds a alarm.

T4 compairs the P1 slider voltage with the output voltage. Then the P1 slider voltage is 0,65 V higher than the adjusted voltage, T2 opens, which stops the T3-T5 Darlington base current.
The 18V, 1A transformer voltage must be filtered with B1 and C1. When the output current is more then 500 mA, the Bz1 starts the alarm (overloading). Bz1 must be a 24 V type, auto-oscillating.

2N3055 variable power supply schematic

variable power supply diagram
This dc variable voltage power supply has not been tested.

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