Effects of Recirculating BEMF to Coil

[rave154]

GOTOLUC,

could you post a schematic for the tests where youre using the 555 circuit, as im having difficulty splitting the power supply for the 555 circuit while upping the power for the coil, i cant quite understand how youve got 170VDC or so going into the coil while only having a low voltage for the 555 circuit.

I dont need the circuitry for the 555 control, just the power connections etc.



David. D

[rave154]

help!

GOTO,

im tearing my hair out trying to figure out how to put 170VDC to the coil, and yet only have an approriate amount of V going to the 555 part of the circuit.

How did you do it?

David. D

[Mark]

I believe he rectified 120AC to get 170v and used a seperate power supply for the 555.

[gotoluc]

Thanks for your test and post David

If you place a capacitor where the bulb is (+ from diode to + of cap & - of cap to other side to complete the circuit) like I did in test 9 and the motor is a low voltage DC motor it should start turning when it is connected to the capacitor.

If you have the motor in series (like I think you did) it will be pulsing the recirculating side as it turns and creating a rotating switch to which can be entertaining also.

Have fun and thanks for posting your results.

Luc

[Hoppy]

Hi Hoppy,

the duty cycle has no importance here and the frequency of 1.5Khz is high compared to something like grid frequency @60Hz. Also, the output side in the test is DC because a capacitor is there to smooth out the output. My test is comparable to DC.

Luc

Luc

I must admit I'm not clear on your circuit you used for this demo and may have made some incorrect assumptions.

Hoppy

[gotoluc]

Interesting way of measuring in video number 9. However Im not totally sold on how it was done. Perhaps try this.

Measure the voltage drop of the single battery, and create a ratio, voltage drop / initial voltage.

Measure the voltage drop of the 9 batteries, and create the same ratio, then compare the two.

In all fairness, I think that this has way to many variables to be too accurate, but it should give a decent idea.

Just a thought.

Hi Armagdn03,

thanks for your post. I was not sure myself if this was an acceptable method of calculation. Looking at it now I don't think it is. I can redo the test but use resistors (Ohms Law)

Here is a suggestion test I can do using 10 new batteries in series feeding the circuit with a specific value of resistor as load and compare it to another set of 10 new batteries in series with only a specific value of resistor as load. Both tests could be started together with the same voltage at the resistor on start up on the pulse circuit as the straight DC and we can monitor the voltage drops to see which way is more efficient. All I need to know is the resistive values to use. It could be a 1K Ohm for the straight DC 10 batteries test and 100 Ohm for the 10% or so duty cycle circuit.

Do you think this would be a fair test?

Luc

[gotoluc]

GOTO,

im tearing my hair out trying to figure out how to put 170VDC to the coil, and yet only have an approriate amount of V going to the 555 part of the circuit.

How did you do it?

David. D

Hi David,

I see your post and I'm looking to see if I can find the 555 PWM circuit that I'm using.

I'll post something soon

Luc

[gotoluc]

GOTO,

im tearing my hair out trying to figure out how to put 170VDC to the coil, and yet only have an approriate amount of V going to the 555 part of the circuit.

How did you do it?

David. D

David, are you using a mosfet on the high voltage side? The 555 is only used to trigger the mosfet (not the coil) which connect the negative of the high voltage to the coil. The coil positive should not be going in the 555 circuit.

See my circuit.

Luc

[rave154]

GOTO,

if i understand you correctly then..

then 555 circuit has say a 12VDC source....and the mosfet/coil has a higher (170V) DC source, with a common ground?

David.D

[rave154]

GOTO, in other words,

the lil "pulse symbol" in the circle represents the 555 circuit AND its own power supply with a common ground to the HV ground of the cap?

[rave154]

GOTO & others,

i have successfully implemented your circuit ( the one with the HV cap as the source for the coil ) together with a small 9V source for the 555 side. i'm using 3 x 12VDC batts in series for the coil side power supply.

i just connected the small DC motor in place of the "output" bulb WITHOUT a cao like you suggested and it runs !!!...pretty fast, not full speed for sure, but not slow either...all of this is with the "input bulb" not even glowing at all ( by careful adjustment of freq & duty cycle )

how very "entertaining" !!!!!!!!!!!

David. D


hmm....let me try the bulb and motor in series & then parallel....brb...


ok, in parallel, the motor runs but barely, only takes a breath of wind to stop it( which it sometimes does stop btw)....however, when its running the "output bulb" is not lit at all, if the motor stops the "output bulb" lights to about the same brightness as if the motor were not in the circuit ... now for series test...

ok, in series, motor runs AND the "output bulb" lights, the motor is maybe not quite as fast as when its just the motor in the circuit...and the bulb is about the same as when IT is the only thing in the circuit....if i stop the motor then the bulb goes a lil brighter, not too much..

again, all of this with the "input bulb" ( negative side of the mosfet ) not glowing AT ALL ( at least not visibly to my eye )...

of course, if i switch out the recycling of the flyback, the motor stops and the bulb goes dead( output bulb).


oh what FUN & ENTERTAINMENT, its like being at the circus as a kid again !

[rave154]

addendum

I should add, the coil i am using is the primary from a 240VAC (4KV) microwave oven transformer. dont know if this is significant or not.

[rave154]

scpoe stuff

oki, using a sensing coil, which is a coil taken from the fan-motor of a microwave oven of a type very similar to the one GOTLUC used in one of his resonance vids where he pulsed it using a function generator as i recall...

im getting 0.4 V peak-to-peak with the coil held directly over the centre of the MOT core and about 2 inches away from it !"....also.the wave form is steady..but..also it has a 2nd "rythym" to it in that the shape of the wave is steady and very discernable but about once every second there is a pulse which disturbs it.....the shape is very osscilatory in nature gradually diminishing to a flat line..

the secondary pulse is about every 0.8 seconds....almost lookes like breathing or a heart beat.

with the sense coil sat plum on top of the core, i get 1.1 V peak-to-peak.

with the sense coil level with the primary...ie... on the same level top to bottom and as close as i can get it...i get 3.1V peak-to-eap....also just had a lovely lil HV shock off the MOT secodanry ! oucha

get out those old MOT's fellas !!!

David. D

[gotoluc]

Glad you got it sorted out David and now having fun.

If you add a capacitor like I described above your motor maybe a little more stable. Just make sure to have the motor connected to the capacitor when you start the circuit since the cap charges fast if it has no load and could explode if it goes above its voltage rating.

The coils that gave me the best results are high Inductance (many winding) but they need to be low resistance (thick wire). Your MOT primary is definitely low resistance but does not have many turns, so it is low inductance.

Thanks for sharing your experience.

Luc

[rave154]

a bit more

using an analogue ameter inserted into the 555 circuit, its drawing 7mA from a 9v battery,

same meter on the 36V supply to the coil is giving 10 mA,

voltage across "input bulb" using analogue meter set to DC giving 0.4V

as above but set to AC giving 1.0V

voltage across "output bulb" using analogue set to DC giving
1.7V(motor running)

as above but set to AC giving 3.0V( motor running)

voltage across motor with analogue set to DC giving 4.6V(motor running)

as above but set to AC giving 10.5V(motor running)
----------------

voltage across "output bulb" using analogue set to DC giving
3.0V(motor not running)

as above but set to AC giving 6.0V( motor not running)

voltage across motor with analogue set to DC giving 1.8V(motor not running)

as above but set to AC giving 3.0V(motor not running).


hope this helps

David. D