lighty

Hi Audioguru I seem to be having a problem, I've just finished the second board and while testing, C7 explodes into pieces about a 1 or 2 seconds after I power up, I replaced it and the same thing happened again. The transformer is the same one I use on my other board, so it can't be it. any idea where I can start? as I can test without powering it up? When I powered it up the 2nd time, I had my meter on the output, and it seemed to sit at about 30V. C7 where 10uF 50V electrolytic. Thanks

Cool, I'll try replacing it. I did notice when I was fiddling with the setting that the output dropped to about -0.3 V. I think I will try replace C7 1st then test it again, perhaps the offset is way off?

Ok, the POTs are working fine, just that when the current is turned down to 0, the limiting LED turns on, could this be because C7 is an electrolytic type?

:-[ Damn, I messed up again, I've used 100K on for the POTs and not 10K..... Thanks Audioguru.....

Sorry Audioguru, I think I wasn't clear, the current limiting function is working when adjusting on the POT, but the VR3 "MAX" limit doesn't seem to be working. Since my transformer is only 125va, I need to limit the maximum at 3A prevent any damage.

Hi Audioguru I've used the TLE2141 opamps. I used Redwire's Eagle BRD along with your parts list. OK OK, :-[ Stupid me, I had the wipers from the POTs connected incorrectly, not meant to be in the middle screw... >:( But I still have one problem, I can't seem to set the max current limit by means of VR3. I have shorted the output though my meter, and no matter the adjustment of VR3 the current rises over the 4amp mark when I quickly increase and decrease the current POT setting. What else could I have messed up with?

Hi All I'm having a bit of a problem with the adjustments... 1 - With the current pot set to min the current limit LED lights up, and it has a MIN voltage of about 100mv, can't get it any lower by adjusting RV1. 2 - I find RV2 makes no changes to anything when adjusting? 3 - The Voltage pot is LINEAR, but behaves like a LOGs, when adjusting the voltage, anything over say about 10V becomes extremely difficult to dial into, when you get to about 14V the current limiting kicks in, and the POT is SO SO sensitive. Same applies with the current limiting LIMIT adjust (RV3) behaving the same way, changes the limit from about 1A to 2.5A with about 3/4 turn on a 20 turn VR. 4 - I also only seem to get a max of 2.5A output. Thanks in advance

Thanks Guru, I'll have to try and test!

If I had to run the output from this PSU to a PWM controller, would this have any ill effects on the PSU, even when current limiting? PWM will run at a 1khz.

Thanks Hero999 I'll just coat with a lacquer too once soldered.

OK, so I ecthed my first double sided boards, not too bad if I say myself! :) Just need to trim and drill. hopefully will have a the components early next week. Stupid question, but how do you get the board that nice green colour? is it the protective stray or a differnent type of board?

Ok, RS Components can order the TLE2141 into the country for me, but its going to take just over a week for them to arrive :( Serously, no one else can supply. :o

Hi All I'm wanting to build one of these supplies too, but neither of the 2 opamps are availible here in SA. My transformer is rated 25V @ 5A AC, therefore open rectified voltage will be 35.4V, what other Opamps are recommended that I could use? Thanks in advance!