Philip,

An RM core isn't designed for operation at 50Hz.  You probably can't get 
enough turns on the core to make it work there.  Try 50kHz, you'll have 
better luck there (and you'll need less turns).

Dave

Philip Pemberton wrote:

>In message <5eeda4c20510020944u53a561dcgd8da86737fe2772e@mail.gmail.com>
>          Vasile Surducan <piclist9@gmail.com> wrote:
>
>  
>
>>Your pseudo sinusoidal signal it's a variable amplitude rectangular
>>one (multiple rectangular steps with different amplitude and constant
>>step size ?) or other sort of signal with constant amplitude like PWM
>>?
>>    
>>
>
>It looks like this on a scope:
>+    ___
>    |   |
>0 __|   |__     __
>           |   |
>-          |___|
>
>I think I've worked out the timing - the 0V segments last for t/6, the + and
>- pulses last for t/3. "t" taken to mean "time for one cycle"
>
>What I'm trying to work out is a way to find the resonant point of the
>transformer. The usual method is to feed a sine/square wave to the primary
>and watch the secondary on an oscilloscope. The problem being I have a scope
>but no signal generator. I was thinking something along the lines of a PIC
>with internal ADC, a diode/capacitor filter, then some code to sweep the
>entire frequency range and store the timing figures that produce the highest
>voltage. Which means I also need to find some resistors to build a voltage
>divider for the A/D input, and maybe a voltage reference chip. This is going
>to take some planning.
>
>I can get 7Vish out of the transformer with normal square wave driving, but
>the transformer is as noisy as hell when I do that. Using a modified square
>wave gets the noise down, but the voltage goes through the floor.
>
>The transformer primary is 270 turns of 28SWG Enamelled Copper wire on an RM
>core, secondary is 150 turns on the same RM core. Design frequency was 50Hz,
>though that produced a rather lame 2V output. It should - in theory - work up
>to 500mA. Of course, theory almost never matches real life.
>
>What I'm trying to do is convert 12V DC into 6.3V RMS AC or 6.3V DC, with a
>10% tolerance (about 5.6 to 7V) for a CRT heater. One end of the heater is
>connected to the cathode, which floats at around -600V (IIRC). Much fun.
>
>Later.
>  
>


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist