Steve Thompson wrote:
>
>
>Larry Carman wrote:
>> OK... you all have sold me on the idea of using zeners instead of standard
>> diodes. At least by using standard diodes I have determined the bias voltage
>> I need. Now I have to find a zener supplier that will accommodate a poor
>> mans budget.
>> Regards to all and thanks for the info.
>How does a smaller diode with a big transistor fare (for example, see
>the very bottom of http://i5uxj-2.cln.it/amp/schemi/w6sai/w6sai.html) -
>or a big transistor with a TL431 as in the G3SEK 'triode board'? Either
>will likely be a lot cheaper than a high power zener.
Sorry, I'm pushed for time at the moment, and unable to reply in great
detail.
The circuit for a high-power 'adjustable zener' comes straight from the
TL431 data sheet. Both WD7S and I have used it in our triode control
boards, because it gives a highly stabilized bias voltage that is also
fully adjustable.
The schematic is in my Triode Boards manual, downloadable from the
website below.
Somewhere in the AMPS archives is a cost breakdown that showed this
circuit works out cheaper than a 50W zener at new-parts prices (try
searching for "TL431").
On the road again tomorrow...
--
73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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