Method to Dump cap voltage to Battery

[shubhamforme]

charging my aa 1.2v nimh batteries with cap pulsing

The battery is charged at 15.5, so you need 30.1 volts to be in the ballpark.
John B

hi,, i am trying to pulse charge my aa batteries 1.2v with a joule thief circuit which puts out 135 v,,,i want the cap dump at 15 volts every time. so i am using a 15 volt zener with a in4007 diode..
i have few question for you,,,
1.is it necessary to use a In5408 diode always...can we use others like 1n4148 or in4007

2.can we use any volt zener diode ,,,as in 15 v,36v,90v?? if my cap is charging up to 135 volts then can i use any zener diode below 100v??

3.also is there any way of attaching an led to the scr so that it blinks every time it discharges the capacitor???

4, can i use an triac also ???

5.are there any type of calculations for which i need to put the zener diode in the scr?? as in if the capacitor reaches a vlotage reading upto 130volts then only a zener diode upto 30volts will work or maybe a larger value zener will also work???

6.is there some power loss when we pulse charge the batteries with an scr????

link for the circuit--

Free File Hosting & Video Downloads, Free File Sharing, Online Friends Network - Ziddu


.. i am using this circuit ...but i dont think its working properly...


waiting for your expert comments...

thanks
shubham

[Farmhand]

hi,, i am trying to pulse charge my aa batteries 1.2v with a joule thief circuit which puts out 135 v,,,i want the cap dump at 15 volts every time. so i am using a 15 volt zener with a in4007 diode..
i have few question for you,,,
1.is it necessary to use a In5408 diode always...can we use others like 1n4148 or in4007

2.can we use any volt zener diode ,,,as in 15 v,36v,90v?? if my cap is charging up to 135 volts then can i use any zener diode below 100v??

3.also is there any way of attaching an led to the scr so that it blinks every time it discharges the capacitor???

4, can i use an triac also ???

5.are there any type of calculations for which i need to put the zener diode in the scr?? as in if the capacitor reaches a vlotage reading upto 130volts then only a zener diode upto 30volts will work or maybe a larger value zener will also work???

6.is there some power loss when we pulse charge the batteries with an scr????

link for the circuit--

Free File Hosting & Video Downloads, Free File Sharing, Online Friends Network - Ziddu


.. i am using this circuit ...but i dont think its working properly...


waiting for your expert comments...

thanks
shubham

Hi shubham, I'll answer you here since you're not using a panel.

Yeah a triac will work ok I think maybe even better for what you want. You're circuit looks ok. If you use a triac be careful of the pinout, the pins are different, look up the data sheet.

Any diode should work OK, if you want the cap to dump when it reads 15 volts then you must add the battery voltage to the gate trigger voltage (from data sheet) and the diode voltage drop, and the volt or so for the LED too,
then subtract that from the voltage you want the cap to dump at and the answer is the zener value. .

I found sometimes if the input was too much and the zener too small and other reasons, that the SCR just kept conducting and didn't pulse. Is this the problem ? If so the triac might fix it.

The zener can be whatever you like with small cap higher is better, and an LED can be put in series with the diode and zener.

With 135 volts to play with and a 3.5 uf cap I would trigger it with a NE2 neon bulb, that way it is a flasher too, it'll trigger the SCR at 80 volts or so.

Any more questions feel free. You're welcome.

Cheers

[nueview]

a problem with using neons is the what shall i call it the after glow or gas plasma persistance.
Martin

[Farmhand]

a problem with using neons is the what shall i call it the after glow or gas plasma persistance.
Martin

How do you mean ? When I do it the neon conducts triggering the SCR and the cap dumps to battery voltage, the neon goes out almost immediately.

I can't remember having any problems with it.

Cheers

[nueview]

i think it could have to do with the triggering current to the gate i also had a bad solder joint at the gate.
this adds some capacitance to the bulb so it lights bright.
but it does not fire every cycle but rather every other cycle.
Martin