ordered 3 of these cheap pcb's, all workt perfect after a few hours of soldering. Now the main test: the transformer is a 24v ac 90 watt the load is a 10R / 50 watt resistor, I put voltage to 20Volt that's 2amps, all 3 blew up after some while...3x the 2sd1047 broke down, after replacing the 1047 on 1 of the pcb's and again testing 2 of the tl081 blew up... After checking the schematic I see that the tl081 gets almost 30 volt and -5 at power pins, that is nearby max of ic...So I changed this, now the tl081 gets +5 and -5 at power pins... next change put 2 1047 in parralel with an extra resistor 0.33R in the emitter line....all works perfect now, but watch out, if you going to use 3 amps out of this power supply this is near the max of used parts, it can get you into some nice firework, so don't go over 2.5 amps.....Than another nice mod. take out the parts that make the -5 volt that fed the tl081's, than use a 7805 and a ltc660 (or similar) and fed the 081's with the -power with the mod. Now you can also use a dc powersupply for fed this pcb....And make sure you cool the 2sd1047, I use an old 478 + fan intel cpu cooler.... It's a fun project to build, has some flaws but can easily be fixed...

ordered 3 of these cheap pcb's, all workt perfect after a few hours of soldering. Now the main test: the transformer is a 24v ac 90 watt the load is a 10R / 50 watt resistor, I put voltage to 20Volt that's 2amps, all 3 blew up after some while...3x the 2sd1047 broke down, after replacing the 1047 on 1 of the pcb's and again testing 2 of the tl081 blew up... After checking the schematic I see that the tl081 gets almost 30 volt and -5 at power pins, that is nearby max of ic...So I changed this, now the tl081 gets +5 and -5 at power pins... next change put 2 1047 in parralel with an extra resistor 0.33R in the emitter line....all works perfect now, but watch out, if you going to use 3 amps out of this power supply this is near the max of used parts, it can get you into some nice firework, so don't go over 2.5 amps.....Than another nice mod. take out the parts that make the -5 volt that fed the tl081's, than use a 7805 and a ltc660 (or similar) and fed the 081's with the -power with the mod. Now you can also use a dc powersupply for fed this pcb....And make sure you cool the 2sd1047, I use an old 478 + fan intel cpu cooler.... It's a fun project to build, has some flaws but can easily be fixed...

ordered 3 of these cheap pcb's, all workt perfect after a few hours of soldering. Now the main test: the transformer is a 24v ac 90 watt the load is a 10R / 50 watt resistor, I put voltage to 20Volt that's 2amps, all 3 blew up after some while...3x the 2sd1047 broke down, after replacing the 1047 on 1 of the pcb's and again testing 2 of the tl081 blew up... After checking the schematic I see that the tl081 gets almost 30 volt and -5 at power pins, that is nearby max of ic...So I changed this, now the tl081 gets +5 and -5 at power pins... next change put 2 1047 in parralel with an extra resistor 0.33R in the emitter line....all works perfect now, but watch out, if you going to use 3 amps out of this power supply this is near the max of used parts, it can get you into some nice firework, so don't go over 2.5 amps.....Than another nice mod. take out the parts that make the -5 volt that fed the tl081's, than use a 7805 and a ltc660 (or similar) and fed the 081's with the -power with the mod. Now you can also use a dc powersupply for fed this pcb....And make sure you cool the 2sd1047, I use an old 478 + fan intel cpu cooler.... It's a fun project to build, has some flaws but can easily be fixed...

The kit is really excellent.I made a variable bench power supply by using this kit.The detail project is on Instructables https://www.instructables.com/id/DIY-Bench-Power-Supply/ https://youtu.be/p50oae_Nnq0

The kit is really excellent.I made a variable bench power supply by using this kit.The detail project is on Instructables https://www.instructables.com/id/DIY-Bench-Power-Supply/ https://youtu.be/p50oae_Nnq0

The kit is really excellent.I made a variable bench power supply by using this kit.The detail project is on Instructables https://www.instructables.com/id/DIY-Bench-Power-Supply/ https://youtu.be/p50oae_Nnq0