[Boatanchors] High Voltage 400 Hz Supply (David C.

[Paul Kraemer]

Or, since good audio generators have 600 ohm output you can drive a 600 ohm 
audio transformer or  power transformer primary directly and use the level 
control on the generator. Take the high voltage direct off the hv winding.
Verify the output with a TRMS voltmeter (like Fluke 78) and you will likely 
be more accurate than the meter you are attempting to calibrate.
Paul K0UYA
----- Original Message ----- 
From: "Drew P." <drewrailleur807 at yahoo.com>
To: <boatanchors at mailman.qth.net>
Sent: Tuesday, January 10, 2012 11:32 AM
Subject: Re: [Boatanchors] High Voltage 400 Hz Supply (David C.


David C. Hallam wrote:

> I am considering various ways to build a HV 400 Hz supply
> to calibrate AC VTVM's. Current requirement is obviously low and I
> need variable voltage up to 300VAC, So what I need is some type of
> an inverter to convert from 60 Hz to 400 Hz and a transformer to step up
> to 300V. As I see it, the inverter needs to have a voltage variable
> output, or can accept a variable line input from a 120V 60Hz variac, or I
> need a 400 Hz variac to put on the output.
>
> Since this will have very limited usage, cost is
> important. Any suggestions on how to do this at low cost?

You might try a sine wave audio generator set to 400 Hz, feed that into a 
hi-fi amplifier (soiled state of course), then feed that into a step-up 
transformer. A 60 Hz transformer will do; you might try a combination of 
filament-type transformers with the low voltage windings in parallel and the 
high voltage windings in series to get the voltage you want.   A good 
single-transformer source might be salvage from a vibrator power supply. 
Another might be a power transformer intended for vacuum tube applications; 
use the filament winding for the input and take output from the HV winding 
which would normally be used for B+ supply. It would be well to add a light 
resistive load to the secondary of the transformer(s).

The volume control would set the output voltage.

Drew

______________________________________________________________
Boatanchors mailing list
Home: http://mailman.qth.net/mailman/listinfo/boatanchors
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Boatanchors at mailman.qth.net

List Administrator: Duane Fischer, W8DBF
** For Assistance: dfischer at usol.com **


This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html