I'm dcyoung9. New on this site.
I'm retired, my career was in computing.

I started in 1964 when about all we had was punched cards and tab machines.
The first real computer I actually worked with was a 1401G.. It had 4k of memory
(magnetic bead core memory) and took up the whole room.

My electronics education is from RADIO SHACK, The internet, reading books, and people like you.

So as you can guess there is still a lot of this electronics stuff I don't understand.
My biggest and most difficult project ever was building a working CESIUM VAPOUR
MAGNETOMETER. TOOK me 2 years and a lot of help from people like you on the internet. Getting parts and learning what some of them were or how to make them was really a chore.

John M. Stanley, a geophysicist in Austrailia, was of tremendous help.
Another physicist who knew all about optics told me how to make a circular polarizer.
Xerox Corporation sent me a sample of polaroid polarized film to make it.
EG&G helped me out with a functional cosmetic reject cesium lamp.

Enough about all that. I'm sure you get the idea.
Now for my first post. And I have several questions for any of you. Be assured I do
appreciate any help and guidance regarding this post.

Here is a circuit I am working on.
I want to charge and discharge a capacitor into an inductor.
I've been looking at this calculator site to help in designing my circuit.
http://mustcalculate.com/electronics/capacitorchargeanddischarge.php?vfrom=20&vto=1&vs=0&c=120u&r=.5

The parameters I put in for charge are: Fm V =1, To V=20, Supply=24V, Cap=120u, Res=1 The result I get is: it will charge in 200 u sec, 23AMP, 529 W

The parameters I put in for discharge are: Fm V =20, To V=1, Supply=0, Cap=120u, Res=0.5 The result I get is: it will discharge in 180 u sec, -40 AMP, 800 W

First question: Will it work?
What needs to be changed?
What do I have to do to this circuit to acheive these results?

Don't have a clue how to get the resistance of 1n4004. arbitrarily plugged in 1.
I'm told that capacitors also have a resistance factor. ???
The fet on resistance is 0.11.
Resistance of 13' #10 wire = 0.013
Arbitrarily used .5 ohm on discharge.
Used 200uS for positive half of symmetrical square wave from 555 timer.

The 24V supply is made up of 5800 mA lithium batteries.
Peak amps is 23 A. Is that possible for the power supplied or do I need more?
Placement of D2 to protect the FET? is it correct?

 

Your question is "will it work" - but there is no definition of what "working" is?
Provide more information / context and you will get better response.

 

Your question is "will it work" - but there is no definition of what "working" is?
Provide more information / context and you will get better response.

Your question is "will it work" - but there is no definition of what "working" is?
Provide more information / context and you will get better response.

Will it work? Will it charge and discharge the capacitor as defined by the calculator examples provided?
Will it charge and discharge the capacitor at all?

 

No.

The problem is that the MOSFET's are not going to work as you want.

Q3 is connected as a "source follower" - the capacitor will never charge to more than the voltage applied to the gate.
As the cap charges, the Vgs approaches zero, the cap charging rate will decrease and the final value will converge very slowly.

Same problem with Q2, you use 50% of the capacitors charge voltage (R4/R2) to drive the gate, as the cap voltage drops, so does the gate voltage, you again end up with a loooong tail on the discharge.

Please disclose the final application, so we don't have to play 20 questions.

 

Also the transistor, because of the resistor in the emitter, will not pull TP1 down to ground. Move that resistor to the base of the transistor.
Is this supposed to be a transmitter?

 

No.

The problem is that the MOSFET's are not going to work as you want.

Q3 is connected as a "source follower" - the capacitor will never charge to more than the voltage applied to the gate.
As the cap charges, the Vgs approaches zero, the cap charging rate will decrease and the final value will converge very slowly.

Same problem with Q2, you use 50% of the capacitors charge voltage (R4/R2) to drive the gate, as the cap voltage drops, so does the gate voltage, you again end up with a loooong tail on the discharge.

Please disclose the final application, so we don't have to play 20 questions.

No.

The problem is that the MOSFET's are not going to work as you want.

Q3 is connected as a "source follower" - the capacitor will never charge to more than the voltage applied to the gate.
As the cap charges, the Vgs approaches zero, the cap charging rate will decrease and the final value will converge very slowly.

Same problem with Q2, you use 50% of the capacitors charge voltage (R4/R2) to drive the gate, as the cap voltage drops, so does the gate voltage, you again end up with a loooong tail on the discharge.

Please disclose the final application, so we don't have to play 20 questions.

WOW! Why didn't I see that? I do now. Thanks! Looks like I have some research and some
work to do.
I'm hoping to use it as a pulse transmitter when I'm done.
I'll need two of them. One around 500Hz another about 700Hz.
Supposedly, there are certain features in the ground that act as a mixer returning the heterodyne signals.
I've done some experimenting using the principal of ground radio. I'd like to get away from having to drive
6 metal stakes in the ground when I change the search area by making the transmitters and receiver portable.

 

Also the transistor, because of the resistor in the emitter, will not pull TP1 down to ground. Move that resistor to the base of the transistor.
Is this supposed to be a transmitter?

Thanks for your reply. I think I probably just need to remove it and wire it to ground. There is a pull down
at the gate of the first FET close to TP1A.
Seems I have much bigger problems as well as this one.
I'm hoping to use it as a pulse transmitter when I'm done.
I'll need two of them. One around 500Hz another about 700Hz.
Supposedly, there are certain features in the ground that act as a mixer returning the heterodyne signals.
I've done some experimenting using the principal of ground radio. I'd like to get away from having to drive
6 metal stakes in the ground when I change the search area by making the transmitters and receiver portable.

 

Hi All,
Well it's been a while but I'm finally back from trying to learn about FETS and IGBTs .
I had so much wrong in my original schematic and I still have a lot more to learn.

During the time I've been doing all this reading I've run across several other applications for this
principal.
I've come up with a new basic circuit using pulsed capacitor charge / discharge.
What I decided to try was to redo the circuit and make it a Pulsed Magnetic Therapy device for
the little dog we have with a back problem that the vet can't help her with. (What have I got to lose?)
Attached is what I've come up with and it appears to work. (Even may be helping the dog. )

The control signal is about 160 Hz, about 60% duty cycle.
The Charge cycle is the positive half of the square wave and is isolated from discharge cycle by D1.
Low part of cycle is Discharge.
Power supply 10V. NOTE!! (At 12V the coil gets a little too hot.)
Current about 2A.

Coil resistance 1.8 ohms, Inductance ?
Peak to Peak pulse across coil 20V.

Discharge Power fets even with heat sinks still get quite warm at 10V. ??
What do I need to do to make it better or what needs to be fixed?
Thanks for your help.

 

Also the transistor, because of the resistor in the emitter, will not pull TP1 down to ground. Move that resistor to the base of the transistor.
Is this supposed to be a transmitter?

No.

The problem is that the MOSFET's are not going to work as you want.

Q3 is connected as a "source follower" - the capacitor will never charge to more than the voltage applied to the gate.
As the cap charges, the Vgs approaches zero, the cap charging rate will decrease and the final value will converge very slowly.

Same problem with Q2, you use 50% of the capacitors charge voltage (R4/R2) to drive the gate, as the cap voltage drops, so does the gate voltage, you again end up with a loooong tail on the discharge.

Please disclose the final application, so we don't have to play 20 questions.

Also the transistor, because of the resistor in the emitter, will not pull TP1 down to ground. Move that resistor to the base of the transistor.
Is this supposed to be a transmitter?

Also the transistor, because of the resistor in the emitter, will not pull TP1 down to ground. Move that resistor to the base of the transistor.
Is this supposed to be a transmitter?

Albert, I've posted a revised circuit diagram using capacitor charge discharge. It is supposed to be a pulsed magndtic field generator. Trying to see if I learned anything or what I don't yet undersrand about

Also the transistor, because of the resistor in the emitter, will not pull TP1 down to ground. Move that resistor to the base of the transistor.
Is this supposed to be a transmitter?

Hi, Albert and Sensacel, I've posted a new circuit diagram using capacitor charge discharge. It is supposed to generate a magnetic field for PMF therapy. Would you guys look at it for me and tell me what I've overlooked or don't understand... Thanks!

 

No.

The problem is that the MOSFET's are not going to work as you want.

Q3 is connected as a "source follower" - the capacitor will never charge to more than the voltage applied to the gate.
As the cap charges, the Vgs approaches zero, the cap charging rate will decrease and the final value will converge very slowly.

Same problem with Q2, you use 50% of the capacitors charge voltage (R4/R2) to drive the gate, as the cap voltage drops, so does the gate voltage, you again end up with a loooong tail on the discharge.

Please disclose the final application, so we don't have to play 20 questions.

Hi, Albert and Sensacel, I've posted a new circuit diagram using capacitor charge discharge. It is supposed to generate a magnetic field for PMF therapy. Would you guys look at it for me and tell me what I've overlooked or don't understand... Thanks!

 

Hi, Albert and Sensacel, I've posted a new circuit diagram using capacitor charge discharge. It is supposed to generate a magnetic field for PMF therapy. Would you guys look at it for me and tell me what I've overlooked or don't understand... Thanks!

dcyoung9, what is PMF therapy?
I do not know what that therapy is. It appears to me that you are trying to charge a capacitor with a dc voltage, then discharge the capacitor to charge the inductor? It this a one time thing, or do you want the charge the capacitor with the inductor discharging. Then repeat the cycle for a certain time? I sounds like a resonate circuit function to me.

 

Dis/charging a cap thru a resistor is different than thru an inductor.

What is ground/radio mixing?

Are you trying to excite something in the ground?

 

dcyoung9, what is PMF therapy?
I do not know what that therapy is. It appears to me that you are trying to charge a capacitor with a dc voltage, then discharge the capacitor to charge the inductor? It this a one time thing, or do you want the charge the capacitor with the inductor discharging. Then repeat the cycle for a certain time? I sounds like a resonate circuit function to me.

Sorry I should have said PEMF Pulsed ElectroMagnetic Field. The practical, proven application is in the field of orthopedics in accelerating the healing of broken bones etc. The main reason for this circuit was to see how/if I could make a circuit that used repetitive capacitor charge discharge. Many think this might be a cure for anything and everything. No real proof that it is a cute for anything other than in orthopedics.
Eventually I want to make a circuit I can use with my Cesium Vapor Magnetometer using a magnetic field generator for Sub Audio Magnetics (SAM) surveys. I published it here to get some help using power fets. My first try was a real failure and it has taken me a month of reading the net to learn how to correct it. So anything you see that is messed up or anything I can improve I would appreciate it. THANKS!

 

Dis/charging a cap thru a resistor is different than thru an inductor.

What is ground/radio mixing?

Are you trying to excite something in the ground?

Certain features in the ground cause signals to mix when two signals encounters them.
The signal expected in returned from two transmitted signal is the heterodyne of the two transmitted signals.

Ground radio is accomplished with two stakes in the ground the other is the signal (radio, pulse, etc). The receiver is nothing more than two more stakes some distance away. Ground and signal (earphone and amplifier). The further apart the stakes The further the transmitted distance. Works over HUNDREDS of feet.
Thanks for your interest... Please see my reply to k7elp60 for additional info and another application. Don

Br-549, You mentioned that discharging a capacitor through an inductor is different than discharging it through a resistor. I was aware that there was a difference.
Problem here is I don't know enough to know what the differences are or how the
inductance or reactance etc. affect the circuit. If you can explain in simple term I would really appreciate it. (It's got to be simple as I really don't understand much about working with inductors.) Thanks, Don

 

Sorry I should have said PEMF Pulsed ElectroMagnetic Field. The practical, proven application is in the field of orthopedics in accelerating the healing of broken bones etc. The main reason for this circuit was to see how/if I could make a circuit that used repetitive capacitor charge discharge. Many think this might be a cure for anything and everything. No real proof that it is a cute for anything other than in orthopedics.
Eventually I want to make a circuit I can use with my Cesium Vapor Magnetometer using a magnetic field generator for Sub Audio Magnetics (SAM) surveys. I published it here to get some help using power fets. My first try was a real failure and it has taken me a month of reading the net to learn how to correct it. So anything you see that is messed up or anything I can improve I would appreciate it. THANKS!

Seems like you are talking about a tens unit. I used to build them. In fact I am aware of a orthopedic doctor that was using electrical impulses a number of years ago to accelerate the healing of broken bones.. In fact he published two books about the subject about 30 years ago.
Going one step further, There was a period of time in which tens units required a doctors prescription to purchase them.
I have even built equipment to inject audio power into the earth using brass welding rods spaced a distance to match the impedance of the earth.

 

Seems like you are talking about a tens unit. I used to build them. In fact I am aware of a orthopedic doctor that was using electrical impulses a number of years ago to accelerate the healing of broken bones.. In fact he published two books about the subject about 30 years ago.
Going one step further, There was a period of time in which tens units required a doctors prescription to purchase them.
I have even built equipment to inject audio power into the earth using brass welding rods spaced a distance to match the impedance of the earth.

I had to go on the net to find out what a tens unit was and to my suprise I own one. LOL. My wife gave it to me for Christmas a year ago. Never used it much. Has all kinds of attachments to stimulate feet and all kinds of stuff.
I was really fascinated when I found out how much energy you could store and release using a capacitor.
It is almost unbelievable to me that guys are using this to shrink a quarter down to the size of a nickel in an instant. All I want to do is induce a strong magnetic field into the ground. My little unit only produces a max of 2000 to 3000 u tesla. Not a lot. The attached is what I got the idea from. Bob Becks magnetic thumper.
Now that I have a circuit that works I need to make one strong enough to really do something with. I would be interested in knowing more about your through earth audio. What I did was generate a tone with a 555 timer, ran it backwards through a 110 to 9V transformer to get a couple 100 V. Was able to pick it up at over 100 ft with a little tl071 amp.

 

I had to go on the net to find out what a tens unit was and to my suprise I own one. LOL. My wife gave it to me for Christmas a year ago. Never used it much. Has all kinds of attachments to stimulate feet and all kinds of stuff.
I was really fascinated when I found out how much energy you could store and release using a capacitor.
It is almost unbelievable to me that guys are using this to shrink a quarter down to the size of a nickel in an instant. All I want to do is induce a strong magnetic field into the ground. My little unit only produces a max of 2000 to 3000 u tesla. Not a lot. The attached is what I got the idea from. Bob Becks magnetic thumper.
Now that I have a circuit that works I need to make one strong enough to really do something with. I would be interested in knowing more about your through earth audio. What I did was generate a tone with a 555 timer, ran it backwards through a 110 to 9V transformer to get a couple 100 V. Was able to pick it up at over 100 ft with a little tl071 amp.

View attachment 162888

I would not recommend building this circuit as shown. I would use a isolation transformer, or better yet a stepdown transformer, for safety reasons.

 

I would not recommend building this circuit as shown. I would use a isolation transformer, or better yet a stepdown transformer, for safety reasons.

Not me either.