Steve Anderson wrote:Harry, is the 800V DC result with the 240V AC into the doubler - I really hope so! If it is, good. If it's with the 480V AC into the doubler something is very wrong! Switch it off and trace everything.
The transformer gives 247 volts and 270 volts .......247 is feeding the positive voltage in your circuit and 270 the negative, the voltages are steady no signs of a mistake thank goodness i was very careful testing ...
If it is 800V DC derived from the 240V AC you need to add one more 10uF and one more 1M/1W into the string between C106 +ve and ground making a C107 and R106 as per below, otherwise the caps in that chain will be over-voltaged.
it was the 270 volts ac to try and get a 1000 negative but its dead on negative 800 volts .
The 240/480V must be slightly higher than advertised with no load - expected, but not quite this high. It's a good result anyway.
Yes the positive is a bit higher for that extra 7 volts AC
Steve A.
A few minutes later...also the same idea in the C102/103 chain, a third cap needed. I've modified the diagram and added C103A and R102A...when you've added the additional caps repeat the same exercise at 240V so the new caps will 'form' too.
OK i will have a look i think i can fit another on the board no problems.
I'm now thinking you may have to increase the value of C104-107 as ripple will possibly be a problem. Four 10uF in series = 2.5uF only.
I will build in the extra resistor cap i have another 1 meg and cap handy
When you've added the extra Cs & Rs and they've 'formed' for a while, increase the input volts to the doubler to the nominal 480V and measure the no-load voltages again. After a while make sure each cap has approximately the same voltage across it as the others in the same chain. Let that run for quite some time if all is well.
OK i will run it a bit lower for a start half voltage ....Ok understood will test those caps
Then add the test loads as indicated below in blue, this simulates the loads of the final circuits. Let me know what these final voltages are, I may need to adjust some of the CRT circuit as a result. This test only needs to be as long as it takes you to measure the voltages, but do both at the same time, both loads, a couple of minutes should be enough. Remove the test loads when you have the figures.
Yes need to get the voltages right here to move on ............. bit late tonight but i will try and do this tomorrow after work ...have to track down those load resistors for this last test as well .. i suppose it does just need a little tweaking here and there getting close to the high negative voltage needed ...
On the other post about the next stage the opto coupler to test the brightness i would need to light the led in the coupler to see if the CRT spot and adjust focus and such ? or do you do it another way jumping ahead just wondering .
Still aways to go yet but like the new circuits for my crt you have put up .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.