I would (at least) add some feedback. Voltage divider and
opamp to compare against set value.
Without feedback, the cap would charge to 400V in no time.
Plus a current limiting resistor of 1K in series with the emitter, which
makes a lousy protection but still better than nothing.
----- Original Message -----
From: "jb-electronics" <[email protected]>
To: <[email protected]>
Sent: Monday, July 25, 2011 5:11 PM
Subject: Re: [neonixie-l] Nixie Tube Power Supply: 0..300V @ 30mA max.
Hi,
thanks a lot for all these replies. I am not an engineer, so I am not
familiar with power supply circuitry.
These modules on Ebay are nice, but I would like to build my own meters
around that supply, that would be a waste of these units I think. They are
a tad too powerful for me as well ;-)
I like the PWM idea because it is so simple: Why not rectify some AC
(after two transformers of course) to say 400V. Then use some suited PNP
transistor (which would that be?) that switches the +400V on and off, and
then a cap to smoothen the signal. Probably a rather Spartan design yet,
any improvements? I can tell it is not protected against shorts.
http://www.jb-electronics.de/tmp/400v_adjustable.png
The maximum current is then limited by the transformers that are used,
isn't it?
Thanks again,
Jens
Am 23.07.2011 02:36, schrieb Charles MacDonald:
On 11-07-22 06:51 AM, Tidak Ada wrote:
The background is this: I would like to build a universal power supply
that
can be used to drive all kinds of display devices: VFD tubes with their
50-60V anode voltage, as well as larger Nixie tubes with 300V anode
voltage
and 25mA current.
Any other ideas are quite welcome, too.
Do you really want to BUILD such an item? They are common on test
benches and with fewer test benches using High Voltage devices, they are
found in surplus.
I recently got a nice looking unit with 1-400 volts at about 100ma as a
science lab item. Dial the voltage limit, Dial the current limit. I have
not tried it with an audio amp yet, but it should run fine for Nixie use.
For example have a look at Ebay
Item number: 230649564649
Item number: 150634915051
If you want to look at the OLD school way, My old school test bench as a
Stark Regulated supply, which is one of the schematics at Pacific TV
tubes site. It uses a 6l6 as a pass regulator. The C supply would cover
your VFD requirements. This was surplus from an Old High School lab.
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