Search found 39 matches

by solar3000
Thu Jan 04, 2018 11:00 pm
Forum: General Discussion
Topic: LM 1084/338/317/etc... voltage drop at < 1A
Replies: 23
Views: 4839

Re: LM 1084/338/317/etc... voltage drop at < 1A

Uhhh..huh-huh...problem solved. same circuit. I connected a 20W halogen bi-pin lamp one end to the ground (anywhere) and then the other pin directly to the output, even at the heat sink tab. The bulb lit up and didn't drop a tenth of a volt. The real problem is that shiitie solderless board that I p...
by solar3000
Thu Jan 04, 2018 7:49 pm
Forum: General Discussion
Topic: LM 1084/338/317/etc... voltage drop at < 1A
Replies: 23
Views: 4839

Re: LM 1084/338/317/etc... voltage drop at < 1A

If you measures 34V peak to peak, it would be 24VRMS (34*0.707) 120Hz is expected but says nothing about the current you are sourcing from the transformer. your probablem may not be voltage, it acts like you are running short of current. So if the transformer is 5A ish then maybe the diodes or filt...
by solar3000
Wed Jan 03, 2018 11:23 pm
Forum: General Discussion
Topic: LM 1084/338/317/etc... voltage drop at < 1A
Replies: 23
Views: 4839

Re: LM 1084/338/317/etc... voltage drop at < 1A

OK so did the suggested measurements. Just to humour myself, I measured the bare transformer at 60 Hz. I measured at the point after the rectifier and mister meter says 120 Hz. The bare transformer measures voltages like this: CT is 16 volts. Entire secondary is 34 volts. So would you say this is a ...
by solar3000
Wed Jan 03, 2018 4:41 pm
Forum: General Discussion
Topic: LM 1084/338/317/etc... voltage drop at < 1A
Replies: 23
Views: 4839

Re: LM 1084/338/317/etc... voltage drop at < 1A

I don't have a .33 MLC capacitor. I have a .1 tantalium cap at the input, but like you mentioned, its a little far, about 3-4 inches. I have a really old and heavy oscilloscope, but its filled with animal waste. Can I use a speaker with a capacitor instead, so I can listen to it? Or do I need dog ea...
by solar3000
Tue Jan 02, 2018 7:56 pm
Forum: General Discussion
Topic: LM 1084/338/317/etc... voltage drop at < 1A
Replies: 23
Views: 4839

Re: LM 1084/338/317/etc... voltage drop at < 1A

sorry, my descriptions are all wrong. Just look at the photos.
everything works, it just doesn't work as well as I'd like and it doesnt work as spec.

I guess the real question is, do you see any issues with wiring, wires used; too long, too bent, to far etc...
by solar3000
Mon Jan 01, 2018 9:50 pm
Forum: General Discussion
Topic: LM 1084/338/317/etc... voltage drop at < 1A
Replies: 23
Views: 4839

Re: LM 1084/338/317/etc... voltage drop at < 1A

Yeah, the diodes are ok, otherwise I would have had quite a BBQ. So, yeah, like the first picture in the link you provided.
by solar3000
Mon Jan 01, 2018 6:20 pm
Forum: General Discussion
Topic: LM 1084/338/317/etc... voltage drop at < 1A
Replies: 23
Views: 4839

Re: LM 1084/338/317/etc... voltage drop at < 1A

I should note that the source is a 24 Volt transformer ( probably 6 or 7 amps, twice the weight of a 24volt/2amp transformer ) Rectifier is: two diodes. anodes to the two ends of the transformer's secondary. Cathodes soldered together and wired to transformer's center tap. The DC is buffered by two ...
by solar3000
Mon Jan 01, 2018 6:11 pm
Forum: General Discussion
Topic: LM 1084/338/317/etc... voltage drop at < 1A
Replies: 23
Views: 4839

LM 1084/338/317/etc... voltage drop at < 1A

So, looking at specs for LMs 1084, 338, 317, etc...the basic adjustable 1.2 - ~30 volts circuit is about the same. Whether it be from TI, Nat Semi, NEC etc... I've been testing them on solderless boards. I've dug up some of the one's I've built in the past ( some LM317s, a 1084, etc... ). All of the...
by solar3000
Mon Jan 01, 2018 6:02 pm
Forum: General Discussion
Topic: really old 4700uF capacitors
Replies: 9
Views: 2084

Re: really old 4700uF capacitors

thanks
by solar3000
Sun Dec 31, 2017 9:56 am
Forum: General Discussion
Topic: really old 4700uF capacitors
Replies: 9
Views: 2084

really old 4700uF capacitors

I found a case of common electrolytic capacitors that I left unused for 30 years. Seems to still work. I found one that heats up. But the rest seem to still work. I'm reading about how capacitors have a shelf life of 3 years. How can this be? https://www.google.com/search?source=hp&ei=3yFJWqroN6nEjw...
by solar3000
Sat Dec 09, 2017 10:57 pm
Forum: General Discussion
Topic: unmarked transformer
Replies: 8
Views: 2075

Re: unmarked transformer

Thanks again all.
by solar3000
Mon Dec 04, 2017 6:16 pm
Forum: General Discussion
Topic: unmarked transformer
Replies: 8
Views: 2075

Re: unmarked transformer

OK. Thanks everyone.
I will test them.
I'm likely only going to use the 24/25.2 volts.
by solar3000
Sat Dec 02, 2017 5:23 pm
Forum: General Discussion
Topic: unmarked transformer
Replies: 8
Views: 2075

Re: unmarked transformer

You're right.

The red-black-red are 12-12 v.
The two blue wires measure 4.9 volts.

So you think they are two independent coils?
Will the two coils affect each other?

Will it not be 12-12-5 volts?
by solar3000
Fri Dec 01, 2017 5:08 pm
Forum: General Discussion
Topic: unmarked transformer
Replies: 8
Views: 2075

unmarked transformer

I'm trying to reuse an unmarked transformer. It comes from an EMCO PSR-7 from 1993. I dug it out of the dust from a pile. The transformer has on one side black and white wires for primary. And on the secondary, on top are wires: red-red-black. That measures 24 volts. On the secondary, on the bottom ...