300mfd @300vdc...........source?

[Structo]

Steve and Drumslinger thanks.
I did see that Radio Shack still lists it. That is why I called my local store.
But they said in their district or something that there weren't any or I would have had them had it sent over.
The store that has one is in another city.

What voltage is everybody using?

Or does it even matter?

My D'lite has a 5v tap on the PT so that is what was used on that amp.

Any advantage going to a specific voltage?
Like less noise with a 12v vs a 6v or likewise?

Why did HAD use the 6v CT then use a voltage doubler supply with it?

[dreric]

Why did HAD use the 6v CT then use a voltage doubler supply with it?

Tom

By no means am I an authority on these things but what I've come to believe is that HAD used them cause they were accessible and cheap. Ten years ago Radio Shacks were still cool stores and had significant parts on hand. He's known for using what's on hand, surplus etc. I remember one of Funk's posts where he said that he believed that HAD never did anything the easy way.

Eric

[hitchcaster]

the different filtering values will sound and feel different IMHO. its also a moving target with how loud you run the amp. some guys will like 220uf, maybe others would like more better. i tried 150uf to hear it and it sounded better at low volumes. but turn the amp up and it sounds like crap. so 220uf works for me. im sure higher 300/330uf values would sound better if the amp is played crazy loud. i think higher filtering sounds/feels worse at lower volume settings... just FWIW

[ic-racer]

While we're discussing 124 parts, I called Radio Shack yesterday looking for the filament transformer and they said they don't carry that anymore.
Even though a few stores outside my area show it in stock.
I may just have to order it.

But what I was wondering is what are the specs on that transformer?

On the #124 layout it is shown as a 3-0-3 450ma transformer.
But a 12v regulator is shown as well as 12v relays.
So is this a voltage doubler circuit?

Other schematics show a 12v transformer with a 12v regulator and relays.

If I were to source a 5v or 12v transformer and use the right voltage regulator and relays, that should be OK right?

Yes , voltage doubler. Different from the HRM and later circuit. In fact, I didn't think the 124 had a Radio Shack transformer. It does not say Radio Shack on it. Unlike the HRM 12V transformers that have it stamped right on there for all to see.

Certainly RS could have sold an un-branded 6v one back in the 80s, but I wound up getting mine from Mouser, as RS doesn't have a 6V one anymore.

[hitchcaster]

theres a couple on ebay too

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... _694wt_913

[Joost]

I have the same question Structo had. For a 124 build, I see different relay transformers on the schematic and the layout. I've seen 3.5 Volt, 6V and 12V variations. Which is the right one to get?

[David Root]

6V. Used with a voltage doubler circuit and 12V relays.

Remember with a doubler circuit and rectifier you will only get 28% of the transformer nameplate amps. So if you have three 12V relays that each need 20mA to operate their coils, total 60 mA DC divided by 0.28=required nameplate amps, in this example 215mA. Dumble used a 450 mA rated transformer but 300 would be fine.

He also ran the pilot light off this supply, if I recall carrectly, so make allowance for that, it's an LED so no big deal.

[Structo]

As far as I know the pilot light has always been powered by the filament winding.
But it doesn't matter where you source the power from as long as it is reduced for the LED.