Bedini Comparator Cap Dump

[RS_]

Hi,

This Schematic SNAGs-002, is My 12V version of John Bedini's, 36V Comparator Cap Pulser Schematic, presented at the 2011 conference.....
So I will not go into why he did it this way.......

But your schmitt trigger pulser should do the same job......
the mosfets gates can also be driven by standard Mosfet driver chip's and the 741 op amp or schmitt trigger, triggering the driver inputs........... most of the dedicated Mosfet drivers have something like a schmitt trigger integrated into their input circuitry anyway........

lots of ways to skin this cat..........

[Nityesh Schnaderbeck]

Some Suggestions


Hey there, I admire your efforts on this circuit. I have some suggestions for you, please don't take this the wrong way.

For a start get rid of that opto-coupler(H11D1) and Q1(BD243C), they are not needed in this circuit, and drive the fets/mosfets directly from the op-amp. The opto-coupler(H11D1) and Q1(BD243C) circuit is seriously compromising the sharp switching of your fets/mosfets. Drive the fets/mosfets with 100ohm or 220ohm matched resistors, from the op-amp. Driving the fets/mosfets using an op-amp(741) eliminates the need for R3(10K) and R4(10k). The gates of the fets/mosfets have a parasitic capacitance, so you want to charge this parasitic capacitance quickly by using low resistance driving resistors for a sharp turn on. Also you want to discharge this parasitic capacitance quickly, the op-amp/comparator shorts the mosfet drive to ground when turned off, discharging this parasitic capacitance quickly, so you get a very sharp turn off.

Using a op-amp/comparator alone only maintains the Capture capacitor(C1) at the set voltage. You also need a hysteresis triggering system like a "schmitt trigger" or something. So you can charge the Capture capacitor(C1) to a set voltage and discharge to a set voltage. A "schmitt trigger" can be designed with adjustable hysteresis, to fine tune your cap dump charging system.

"Volty" Your rotary switch is good for, finding the right capture capacitance, but the switch contacts will add, unwanted impedance's, and compromise the charging and discharging capability's of the capture capacitor. If you are only using an op-amp/comparator, changing the value of the capture cap, will not add much hysteresis, if any to the circuit.

I hope this helps.

You can also look at this thread, http://www.energyscienceforum.com/showthread.php?t=2020

[Volty]

Hi alfinip2000,

In my case 100uF did it. We have been discussing that since post #68. If your circuit shows the same symptom first be sure that you are using the correct devices, check if the transistors are getting the correct triggering voltages.

P.S. That cap is not a panacea.

Lman

Hey,

Long time no reads. In this whole thread no one has set up a rotory selector switch for the Hysteresis Cap. I found that to control dumps per second rate, BOTH Cap Charging Bank and Hysteresis Cap must be selectable.

My box has one 4,700uF 50V always connected, which will be dumped, and i have gang switches to add another 4,700uF, than a 10,000uF, and another 10,000uF, for 29,400uF TL. Smaller bank dumps faster.

Selecting a smaller Hysteresis Capacitor also dumps faster and shallower. Adjusting Dump Threshold Voltage back up where it was helps, but the ability to change combinations of capacitors is the very best you can attain i say.



*EDIT - Note that the Dump LED in Mirrored trace Layout is backwards.

[AlvaroHN]

I have never seen fets that cheap unless he is buying them in hi bulk and passing on the savings. if you buy them at 100 price quantity you can get them for 1.38 each from mouser. ask them if they are Fairchild or on semi, what is the brand.
http://www.mouser.com/_/?Keyword=IFR...mosfet&FS=True

I can get some to you also, I have them here. send me an email.
Tom C

ok Tom I just sent you an email

[Tom C]

I have never seen fets that cheap unless he is buying them in hi bulk and passing on the savings. if you buy them at 100 price quantity you can get them for 1.38 each from mouser. ask them if they are Fairchild or on semi, what is the brand.
http://www.mouser.com/_/?Keyword=IFR...mosfet&FS=True

I can get some to you also, I have them here. send me an email.
Tom C

[AlvaroHN]

I am going to build the 12v RS_ comparator, and have a couple questions:

1 - On ebay, there are electronic parts, for example the irfp260 and the price is like 10 for US$ 15.

is that the normal price? or those are pirate parts or something?

2 - if I would like to add a dump indicator led, I could add a led in series with the h11d1 isn't? (led side of the h11d1)

best,

Alvaro

[adys15]

Thanks,i put a bulb in place of the ammeter and it it lights like at 3A no drama

[Tom C]

with an analog meter you are just getting an average, the dump is much faster than a meter can react to. you are probably upwards of 40-60 amps right when the fet opens.

Tom C

[adys15]

Your right Tom,2x bat voltage.but i was refering at dump voltage 15v and 15v in at the coil i measured the amps with an analog meter like John had in the Energeticx video.Thanks

[Tom C]

your comparator should be dumping at 2x battery voltage set at the comparator dump potentiometer. pulse power is hard to see with a meter, the only way to really see it is with a scope and a current probe, hundred amp probe minimum.

Tom C

[adys15]

Hy guys does anybody know how to calculate pulsed power coming from the comparator?I'm getting the same voltage out as in but at 3A once 2 sec

[sergejfa]

RS thanks for your help

[RS_]

C2 will be a ceramic or Mylar in most cases, can be a electrolytic for larger values if needed to tune the on time. the C3 will always be a electrolytic

[sergejfa]

hi RS

what kind of capacitor i need for c2 and c3,ceramic or elektrolytic?

Thanks

[Lman]

Hi alfinip2000,

In my case 100uF did it. We have been discussing that since post #68. If your circuit shows the same symptom first be sure that you are using the correct devices, check if the transistors are getting the correct triggering voltages.

P.S. That cap is not a panacea.

Lman