SWTPC Digi-Vista Nixie Clock

[Allison]

Top posted for brevity.

Most equipment I've worked with run 160-190V for Nixies.  
Further my Yaesu YC-355D freq counter that I purchased in 
1973 is nixie based and also uses around 170V.  FYI: base 
logic is venerable 7490, 7475 and 7441 for the decades.

For a simple PS to run nixies (and valves) I use a 6.3V CT 
600ma or 1A To 117V mains transformer.  They are common 
here in the USA and cheap.  I drive them with a pair of 
bipolar power transistors in TO220 cases from 12V.  Base
drive for those transistors is derived from a squarewave 
source of two phases 180 degrees (555 and 7474 work fine)
at 400hz or so (not criticial, higher makes filtering 
easier and less mechanical hum).  The ouput can be rectified 
and filterd as needed (bridge or doubler is what I do 
depending on voltages needed).  The voltage will be around 
210V with a small load (10ma). If I need more power a 
heavier transformer with 3A or 5A 6.5V winding is used.  Also
if a stable voltage is needed sample the output and use that 
as feed back to a series pass feeding primary side power.
That will regulate very well.  

I've built that many times and run many a HV device and even a
CRT (D170 size) that required 1200V.  For that I used a small
1A 10VCT:230V control transformer and a voltage multiplier and
feedback for regulation.  Works well.

I prefer the driven style rather than self excited voltage 
converter as it's easier starting and has stable operation.
It also doesn't require a special (hard to find or make) 
multiwinding transformer.  the rest of the parts are also
generally easily found in defunct stereos or even ratshack.
Exotica and unobtainium is a pain.


Allison

>
>Subject: Re: SWTPC Digi-Vista Nixie Clock
>   From: "Dave Brown" <tractorb at ihug.co.nz>
>   Date: Wed, 14 Sep 2005 09:59:02 +1200
>     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>
>----- Original Message ----- 
>From: "Tony Duell" <ard at p850ug1.demon.co.uk>
>To: <cctalk at classiccmp.org>
>Sent: Wednesday, September 14, 2005 7:35 AM
>Subject: Re: SWTPC Digi-Vista Nixie Clock
>
>______________SNIP_____
>
>Either way you'll end up with something over 300V DC
>>
>> -tony
>
>Worth pointing out that in general, you don't need anything like 300 
>volts. Most nixies will run very well at no more than 120 volts HT 
>supply-and if you make your own drivers then 300 volt ( cheap and 
>readily available) transistors can be used.
>
>DaveB, NZ 
>
>
>
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