Cap Dump Circuit

[Shanjaq]

tried to edit this in but the forums didn't want to cooperate: The idea here is to jam the switch between its high and low impedance state as fast as possible so it isn't dissipating too much power through the drain-source junction, which would vaporize in short order given the case of a purely capacitive load. If you have multiple power supplies you can communicate control signals between them using a level shifter in a similar fashion to how opto-isolators are used, but response times are much faster.

[BroMikey]

A Few More Diagrams

Cool site Mike

Thanks Dave

Here are a few more 555 timer applications.

BroMikey's Science Projects

These applications to drive NP and PNP do not use any dead time it just switches at the same time. One is "ON" and the other is "OFF"

Mike

[BroMikey]

Explain further

There are a couple of designs for level shifters, but they all boil down to using the high Vceo parameter of BJTs to reach across to the other rail and manipulate things relative to each.

For example:
Level Shifter 1

or

http://www.electro-tech-online.com/a...806-gif.39323/

I do not understand.

Mike

[Shanjaq]

There are a couple of designs for level shifters, but they all boil down to using the high Vceo parameter of BJTs to reach across to the other rail and manipulate things relative to each.

For example:
Level Shifter 1

or

http://www.electro-tech-online.com/attachments/image3806-gif.39323/

[Dave45]

Cool site Mike

[BroMikey]

Circuit applications

Thank you Mr. Jones
What Im trying to do is combine the boost converter and the buck converter into one.
I found a chip that does this but I want to be able to change and experiment with different configurations.

Here's the boost buck chip

https://www.youtube.com/watch?v=MIYyGeLl128

Sorry Mike dont mean to derail your thread.

No need for all of that Dave

You are doing a great job in my book. This all applies.


Mike

[Dave45]

You need a FAN3278. Drive P channel Fet on the high side and an N channel Fet on the low side in a half bridge fashion. Read the DataSheet for an example.
Lots of Half bridge drivers will also control 2 N channels in high and low spots so no need for an expensive P channel fet. N channel Fets are more reliable.

Matt

Thank you Mr. Jones
What Im trying to do is combine the boost converter and the buck converter into one.
I found a chip that does this but I want to be able to change and experiment with different configurations.

Here's the boost buck chip

https://www.youtube.com/watch?v=MIYyGeLl128

Sorry Mike dont mean to derail your thread.

[Matthew Jones]

Yes, but the ic is not made to run the pnp gate.
I have been searching for an ic to run both pnp and npn gates but no luck.
The pnp gate has to have a neg bias and the npn gate has to be pos biased.

You need a FAN3278. Drive P channel Fet on the high side and an N channel Fet on the low side in a half bridge fashion. Read the DataSheet for an example.
Lots of Half bridge drivers will also control 2 N channels in high and low spots so no need for an expensive P channel fet. N channel Fets are more reliable.

Matt

[BroMikey]

Attachments

I am running out of room for attachments so I will be putting my materials here in safe keeping.


BroMikey's Science Projects



This site only allows , I think, 3mgbs? And after 3 months here at this site I have exceeded my amount of space.

This website will be here forever and my work can be seen by everyone desiring to do battery pulsing experiments.

Also some critical text that I have written will also be transferred and placed by the diagram so sense can be made out of the pictures.

So far you will see driver, timer type chips and mosfet circuits to experiment with.

It is better to have it all together.

Mike

[Dave45]

Yes, but the ic is not made to run the pnp gate.
I have been searching for an ic to run both pnp and npn gates but no luck.
The pnp gate has to have a neg bias and the npn gate has to be pos biased.

[BroMikey]

Like this?

The pnp and npn need to be out of phase,,,, I think.
Its the bemf that is collected
pos bemf from the npn pulsed coil
neg bemf from the pnp pulsed coil

In a joule thief the coil is pulsed with an npn transistor and we get a pos bemf which will light an led well, led's take very little current, but to sustain a battery or cap we need both.
pos and neg bemf

Hello Dave did you mean like this?




Mike

[Dave45]

Hi Dave

I think you are on to something there. Nice circuits. What about tying the gates together so when the PNP fires so does the NPN??

I am looking at your circuit now.

Mike

The pnp and npn need to be out of phase,,,, I think.
Its the bemf that is collected
pos bemf from the npn pulsed coil
neg bemf from the pnp pulsed coil

In a joule thief the coil is pulsed with an npn transistor and we get a pos bemf which will light an led well, led's take very little current, but to sustain a battery or cap we need both.
pos and neg bemf

[Dave45]

I should have stated this is a synchronous buck converter, the Q2 switch takes the place of a diode (less loss), the switches are out of phase.
But Q1 should be pnp.

[BroMikey]

Still Thinking

I have been searching for an ic to drive pnp and npn gates and cant seem to find one.
One way to do it is to use an npn transistor to drive the pnp gate.
Most if not all gate drivers that I have found are made to drive one or the other in pairs but not both.


An idea I have been working out for awhile.

Hi Dave

I think you are on to something there. Nice circuits. What about tying the gates together so when the PNP fires so does the NPN??

I am looking at your circuit now.

Mike

[Dave45]

I have been searching for an ic to drive pnp and npn gates and cant seem to find one.
One way to do it is to use an npn transistor to drive the pnp gate.
Most if not all gate drivers that I have found are made to drive one or the other in pairs but not both.


An idea I have been working out for awhile.