The circuit in the schematic is the basic voltage control circuit.
For simplicity I did not add a means for charging the cap.
This is a very simple circuit ......but I thought I would break it down for the people here that are fairly new at building circuits.
This schematic is of the U cap potentiometer and LED.
The dots on the ends of the lines coming from the U cap should be considered as connection points for the original means of charging the U cap.
The potentiometer is used to drop a variable amount of voltage , the LED is chosen to provide an indicator light and drop a more or less consistant amount of voltage .
gary
This shows that the negative side of the U cap and the battery are kept at the same voltage.
The battery is shown as a separate battery it can also be the source battery for the JT charging U cap.
gary
This schamatic shows that the transistor acts as a simple switch that enables or disables the control coil
If the transistor is conducting then the impedance of the control coil drops .
If you have ever used more than one secondary on a JT you know that they must be matched very carefully.
If they are not matched most of the power will go to the lower inductance winding.
This circuit just takes advantage of this simple fact.
As the voltage that remains after the LED and pot reaches a level that starts turning on the transistor the impedance of the winding drops effectively loweing the ability of the JT to charge the U cap.
This turns out to be a VERY soft switch. It is not easy adjusting the pot because the LED does not come on all at once.
I like this quirk because it shows more about the actual charge state then a simple on or off condition.
A zener diode would probably provide a much sharper transition than the LED .
So far the control coil is a secondary on the JT used for charging the U cap.
I plan to test using a separate coil soon.
gary
Edit
I will try to get a few pictures posted in the next few days.
I recommend using small supercaps in place of U caps while building and adjusting this circuit.
I hooked 2 5.5V supercaps in series so I pretty much don't have to worry about going over rated voltage.
gary
Is this just the secondary of the Joulethief?
Quote from: nievesoliveras on November 04, 2010, 05:19:00 PM
Is this just the secondary of the Joulethief?
Jesus
This circuit is for controlling voltage going to a Ultra cap.
The coil circled in red could be called a secondary of the JT.
I added this winding to a JT charger I already had.
I plan on testing a way to use this circuit with a JT charger that has no room on the toroid for another winding.
Soon I will switch to a schematic that shows the JT charger and the voltage control circuit.
I wanted to try to keep it as simple as possible at first........so I only did the voltage control circuit.
gary
My goals for this circuit were
Low parts count.
Common parts only.
Charge indicator light , so I can gauge the approximate charge level at a glance without a meter.
gary
A few more details about this circuit.
A relatively large transistor is needed.
I tried a 3904 ........I could not get it to work.
So far most of my tests have been with a TIP2055
I tried a MOSFET ......couldn't get it working........yet.
I use several meters when expermenting with this circuit.
I monitor the voltage of the primary of my JT charger.
I also monitor my supercap voltage and my charge battery voltage.
I am not currently trying to feed back to the JT battery
This circuit may be easier to make using a candy cane type JT charger.... with the candy cane coils it is very quick and easy to add the secondary for this circuit .
The secondary I am currently using is pretty much identical to my primary winding on this charger.
Both go through the centers of all the toroids.
I stopped using this kind of secondarys a long time ago because this type of secondary will always take priority over the other windings....... it is just to powerful to co exist with the normal secondarys.
gary
Thank you @resonanceman!
You have quite a project there.
The mosfet has to be driven by a small transistor like 2222A or similar.
Jesus
Quote from: nievesoliveras on November 04, 2010, 11:17:26 PM
Thank you @resonanceman!
You have quite a project there.
The mosfet has to be driven by a small transistor like 2222A or similar.
Jesus
Jeasus
Thanks
:)
So if I understand right you are saying that the mosfet setup would have to be kind of like a darlington transistor?
I am still pretty new at building things ......and maybe a little slow.
Can you draw a schematic of how the transistors would be wired?
I think MOSFETS would be ideal .......but the fact that they have little or no current flowing through the base eliminates the LED indicator light.
That is really not a problem because the right sized coil added in series with the control coil could be used to power a LED whenever there is current flowing through the control coil. ( I have done this on a few charger circuits I have made )
gary
It is not Jeasus it is Jesus. We must be clear on that.
The transistor 2n2222a can be changed by a tip3055 if it gets too hot during operation.
Jesus
Quote from: nievesoliveras on November 06, 2010, 10:15:35 AM
It is not Jeasus it is Jesus. We must be clear on that.
The transistor 2n2222a can be changed by a tip3055 if it gets too hot during operation.
Jesus
Jesus
Thanks for taking time to draw the schematic.
It is not exactly as I thought it would be.
But it turns out that I have played with a circuit almost exactly like that.
I didn't play enough with it to get it running like I wanted...... but I did hope to pick up where I left off later.
I was using a TIP2033 where you have a MOSFET and a battery where you have your supercap.
My plan was to use the circuit to pulse an external coil........ In theory almost any coil or ferrite core transformer could then be used as a JT.
gary
Quote...My plan was to use the circuit to pulse an external coil..
Then you must try this other circuit instead.
Be careful with the possible high voltage output.
Post results.
Jesus
Quote from: nievesoliveras on November 07, 2010, 04:45:30 AM
Then you must try this other circuit instead.
Be careful with the possible high voltage output.
Post results.
Jesus
Thanks for the schematic.
Have you made this circuit?
WHat windings did you use for the coil?
It is similar to what I have been working on for quite a while.
The schematic looks very simple but it is kind of trickty to do.
WHen I first started out with my flyback/feedback tests I had to use a load to get it to work. I usually used a 60 or 90 LED array.
These arrays are relatively high impedance.
JTs NEED high impedance.
My flyback feedback tests involved adding coils in series in between the JT secondary and the load.
Most of those coils that I added were fed to a diode bridge and back to source.
I usually needed around 9 extra coils to get the circuit to the self charging state.
The weekness of my flyback/feedback circuits was I had to keep adjusting the base resistance every few hours or it would stop charging .
I have corrected a schematic that I did a month or 2 ago.
It is my complete JT charger with UCVC.
I did not post it before because it had some mistakes.
I think it is right now.
The violet diode is optional in some of the circuits I have made it added up to 2 V to the output. On others it did not help at all.
This schematic is about the basic configuration of the charger.
I still have not settled on the details of the coils
I can get to the self charging state by adding a bunch of small coils together.......or a few larger ones.
I am looking for ways to make a good practical compact coil for this circuit.
So far my candy cane coils are the best I have come up with.
but they are not very compact .....
As with other coils to much inductance will choke the whole circuit.
To little inductance and the JTs voltage will suffer.
With my candy cane coils the # of wraps per toroid and the number of toroids have to be matched to the circuit.
Maybe the best thing about my candy cane coils is , you can add more toroids for more power.
OOpps
I better explain that before we get a bunch of vultures in here.
:)
Any toroid will only handle a specific amount of power .
With my candy cane coils you can add more toroids in series.
The output of the voltage seems to be the combined ratio of the windings on the toroids (Secondary ) and the primary going through the center of all the toroids.
Most of my best candy cane coils have lots of toroids with just a few windings on each ( 2 to 4 winding per toroid.)
What I am expermenting with now is using larger wire for the primary.
I need to get more large wire......like 12 gauge
My first tests with larger wire primary's seem to make a difference
( more electrons entrained? )
The bottom picture is of a candy cane coil lighting a 25W CFL
ALthough it is just barely lit up it is only using .118A
at 4.87V = 0.57466W
Transistor TIP2055
Base resistor 3K
Base pot 5 K but it its lowest resistance .
No tank
42 5 for $1 toroids 4 wraps per toroid .
Primary is 4 wraps ......2 with 12gauge 2 using a previous 2 wrap primary of cat5 bifilar wire.
The CFL will not light up with the 3K resistor .......bypassing the resistor lights the CFL quickly.
I am still trying to get down to 1.5 V .........but it may take a while.
gary
I am just working with the circuit now to drive a car coil. I need to play with the components in orfer to get a good spark at the car coil output.
Jesus
Quote from: nievesoliveras on November 07, 2010, 05:03:51 PM
I am just working with the circuit now to drive a car coil. I need to play with the components in orfer to get a good spark at the car coil output.
Jesus
Jesus
I am not sure what you need sparks for.
Are you trying to make the coil yourself or just get some sparks?.
If you want a quick and dirty way to make a STRONG high voltage JT a MOT will do the trick. ( Mictrowave Oven Transformer )
Back in the days when I was trying to make a JT with anything that had wires coming out of it I scared myself 2 times.
Once was when I made a JT out of a MOT. I fried a 60 LED array a DMM and melted the insulation on some alligator clips.
The other time was when I tried using an ignition coil for a secondary on a JT made from a flyback transformer core.
No real damage this time except alot of smoke and melted insulation from a couple of my alligator clips.
If you used an ignition coil as a secondary for a MOT JT I am pretty sure you would have a very good chance of scaring yourself before you make some really nice sparks
:)
Just be careful.
I am sure that you know that this kind of voltage can be lethal
gary
Edit
Just in case not everyone understands how to use an ignition coil as a secondary ..... just connect one wire of your JT secondary to each of the low voltage posts of the ignition coil
The center post becomes the HV secondary ....... I do not remember exactly what I connected the other end to ......but I am pretty sure almost anything would do.
Now .......I think I would look for a HV cap in the .1uF range and use it to buffer the HV a little then connect that to a HV bridge.......then feed it back to source.
If the voltage drops to low when you connect the cap....... try a smaller cap.
The cap will buffer the impulses just a little and act as a current limiter for your feedback.
gary
I will try to build a coil using a formula.
The formula is:
1. Divide the desired voltage by the voltage you have as source
2. The result is the step up number.
3. Chose a safe number of wire turns as a primary winding
4. Multiply it with the step up number (it gives the secondary turns number)
The circuit driver must be good. I have damaged a lot of parts with the heat produced on the parts.
Jesus