I have been getting interesting results by using a transformer on the mainsm stepping down to around 12volts AC, then a bridge rectifier, on to a beefy IGBT which is given a square wave signal from a commercial signal generator, presently 100 cps, the chopped 12 volts is then fed into a 50 volt to 240 volt transformer, into the 50 volt end, thus getting a high voltage spike from the 240 volt end. The charging of lead acid accumulators and reconditioning, is amazing, however the transformer is losing power when the frequency is raised to say 1000 cps, is there more to be gained pulsing at higher rates? how high should one go? I could get a dust cored transformer if there is more to be gained at higher frequencies. Any answers out there please

This sounds like a dangerous device!!

Hello folks,

I was wondering if someone tried to experiment with solid state air coil and what the results are to compare. I just built another one and it works fine but I can't get the cap pulser to work well. It does with small cap, such as 2 - 3uF at the bridge but anything like 20 - 50uF causes SCR to stay "latched" all the time. As a result I'm basically charging off the bridge and there is no potential build up in the cap. I'm using inverted SCR triggered off the darlington opto and HV transistor. Probably couple MOSFETS will solve a problem but don't really want to go this way if don't have to. I also tried this with a reversed trigger as I did with "cored" SS and SG but it doesn't work with air coil, at least for me.


Vtech

Vtech - I've got an air-cored solid state sg that Ren gave me, and when I hooked it up to an scr cap pulser, I had to keep the cap below 3uF as well. Otherwise, same problem, scr stays latched on.

Reading your post, I'm supposing it is mainly a problem with air cores? That's interesting.

Hello Inquorate, I have built couple chargers with rotors and cap pulser, inverted SCR. The capacitor can be large since frequency isn't that high. I just get some tests reversing trigger and different caps. I put bank of photo caps, 120uF each and got 2500uF in total. I'm sure it will work with higher bank too but may need a beefier SCR.
However, in my iron cored SS I could get as high as 80uF. I did had a success once with 6800uF but I guess pulses were too powerful and SCR latched. I went back to 4uF and left it alone since I need something working and charging my batts.
This is my first air core and of course it oscillate much higher than with a core thus more pulses going into the cap. I had a short luck with 10uF cap (before SCR latched) but couldn't get the voltage under 25V, which is ok for sulfated battery but too much for regular charging, imo.
BTW I'm using 12A 600V rated triac (bipolar switching diode) not a thyristor.
I never came across any detail about this variant, other than J.B patent.
I appreciate you reply.


Vtech

When the cap discharge through the scr to the battery the scr will switch off when the cap side (anode) reach the same voltage as the battery side (cathode)
Now if your radiant pulses charge the cap up to fast, which is good, The scr will never switch off.
What I did was to switch at a higher potencial say 36v. That seemed to work.
I dont think 36v pulses is to bad for the battery.
I used that zener, scr circuit. With a 24v zener on the gate. As soon as as the cap reach 24v + battery voltage (36v) it triggers
I also had to use a larger cap like a 330uf that does not charge up so fast to 36v. Do not use huge caps like 10 000uf. They will short the scr with the first pulse
The circuit I used is on this thread #15
Method to Dump cap voltage to Battery

Thanks Vissie I'll go through this thread tomorrow, I mean latter today I was up too early. I have another idea: what if I'll switch the circuit off while pulsing into the battery?
If you had a chance to see J.B schematic from FEG book, there is a switch (famous S1 ) at the positive from input battery. Knowing John, he wouldn't put the switch there just to indicate how to power off the circuit. I think that is the purpose - switch off while pulsing. This way, primary battery doesn't know what is going on. Does this make sense?


Vtech

No your talking. Is that not what he does in the solar charger?
Isolating the supply completely from the charged cap bank before dumping it to the batteries. He suggested using the bipolar switch to do just that on the tesla switch