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Howto: TeddyReg

Hello,

Got busy for a few days now back to fun... Can someone spare a few of the 100nf film caps that bypass the 10uf tantalum? The last time I tried to order them they were on back order. A few weeks later was told they weren't going to offer a replacement.

Thanks,
M
 
Is it ok to use 1 single long heatsink for the teddy reg - ie one long heatsink for all devices? Do I need to use mica and shoulder washers or will it be ok to just mount directly to the heatsink?

Fran
 
Hi Fran yes you can and yes you do. You will need to insulate each TO220 device from the heat sink with mica insulators and bolt insulators. And a little heat sink compound to ensure efficient heat transfer
 
Still can't get a negative reg to work....does anyone know if LM337s from different manufacturers can have a different pin configuration?
 
PS..just tried a 337 from a different manufacturer from the parts group buy ones and seems to work.......
 
Hi all
What is the maximum voltage a teddyreg can work at, I understand the LM317 is not the limiting factor as this only sees the floating voltage differential, so am I correct in that the D44H11 which has a maximum Collector-Emitter Voltage of 80V is the limiting factor?
Or am I well off the mark.

Tony
 
Having read more on the acoustica site I see the Fet seems to be the limiting device, any ideas, as I would like + & - 55V

Tony
 
The capacitors as well. It's hard to find tantalum capacitors at this size that can withstand 60-70V. Electrolytics will not sound the same, but if you have to, you have to...
 
Isn't the voltage sensitivity on the FET in the Teddyreg application regarding to the dropout over the vbe? Since that usually is in the 2 - 10 V region most devices would be fine here, or am I missing someting?

By the way Tony, where did you score your tants?

/Magnus
 
Magnus
Got the tants off ebay, I will find the company over the weekend. Re the dropout I got the warning about Fet from the Acoustia write up.
 
The issue with the FET voltage rating is the startup transient - the output voltage will still be low while the gate circuit charges up, and so the FET briefly sees pretty much the full voltage.

As far as I know, there are very few 100V rated JFETs, and those that I know of have low transconductance, and so are not a good fit in this application.

I suspect your best bet will be to use a bipolar darlington, which is the arrangement that Teddy used before I suggested the Fetlington circuit to him.

Choosing suitable transistors should not be a big issue; I would go for devices rated at 80V or more.
 
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