Hi,
I am not going after the most efficient design, I just want to be as
simple as possible: Just turning a knob to adjust the voltage.
When do you think the transistor power dissipation is important?
I first toyed with the idea of using a variable transformer, but what I
do not like is the very high current that can easily flow, as well as
the fact that it is much closer to the mains. Just makes me uneasy.
Unjustified? ;-)
Best regards,
Jens
Am 25.07.2011 22:38, schrieb Tidak Ada:
Hi,
Did you realize the power dissipation in the transistor?
Better is to use a tranformer with several taps in a circuit like this.
eric
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of jb-electronics
Sent: maandag 25 juli 2011 19:00
To: [email protected]
Subject: Re: [neonixie-l] Nixie Tube Power Supply: 0..300V @ 30mA max.
Hi,
thanks for the hint. See the reviewed circuit:
http://www.jb-electronics.de/tmp/400v_adjustable.png
Yes, the feedback loop will be included, I forgot to mention that my power
supply will have both a volt- and amperemeter built in.
This way I will be able to check the voltage, as well as to completely shut
off the PWM stage when the current is too high. Is this safe?
Does anyone know a good PNP transistor for this purpose?
Regards,
Jens
Am 25.07.2011 18:08, schrieb Frank Bemelman:
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.
--
You received this message because you are subscribed to the Google
Groups "neonixie-l" group.
To post to this group, send an email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/neonixie-l?hl=en-GB.
--
You received this message because you are subscribed to the Google Groups
"neonixie-l" group.
To post to this group, send an email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/neonixie-l?hl=en-GB.
--
You received this message because you are subscribed to the Google Groups
"neonixie-l" group.
To post to this group, send an email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/neonixie-l?hl=en-GB.
