0-30 Volt 0-1Amp Laboratory Power Supply with 2N3055

This circuit provides 0-30 volts, at 1 amp, maximum, using a discrete transistor regulator with op-amp feedback to control the output voltage. This power supply has constant current mode suitable for charging batteries.

With reference to the schematic, lamp, LP2, is a power-on indicator. The other lamp (lower) lights when the unit reaches its preset current limit. R5, C2, and Q10 (TO-3 case) operate as a capacitor multiplier. The 36 volt zener across C2 limits the maximum supply voltage to the op-amps supply pins. D5, C4, C5, R15, and R16 provide a small amount of negative supply for the op-amps so that the op-amps can operate down to zero volts at the output pins (pins 6). A more modern design might eliminate these 4 components and use a CMOS rail-to-rail op-amp. Current limit is set by R3, D1, R4, R6, Q12, R10, and R13 providing a bias to U2 that partially turns off transistors Q9 and Q11 when the current limit is reached. R4 is a front panel potentiometer that sets the current limit, R22 is a front panel potentiometer that sets the output voltage (0-30 volts), and R11 is an internal trim-pot for calibration. The meter is a 1 milliamp meter with an internal resistance of 40 ohms. Switch S1 determines whether the meter reads 0-30 volts, or 0-1 amp.

Read More Source :
http://members.tripod.com/michaelgellis/power2.html
Thank You.

This entry was posted on Thursday, August 16th, 2007 at 2:10 pm and is filed under Power supply, Variable Regulator. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.