electromagnetic field therapy

[budm]

Re: electromagnetic field therapy

Your meter is not fast enough to measure pulsing DC. If any one of the AND gate goes low, the out put will go low, if one of the gate is pulsing HI-LO, then the out put will be dictaed by that pin that is going HI-LO, the out put will follow that pin.
Also the voltage on the B-E will be clamping at 0.7V max (signal swings between 0 and 0.7v), so the AC value is 0.7VAC peak and it is not sine wave, your meter is also not TRUE R.M.S meter that it is trying to measure 0.7v peak to peak voltage. You need the scope to see that signal both at the Base and at the Collector.

[petit]

Re: electromagnetic field therapy

Your meter is not fast enough to measure pulsing DC. If any one of the AND gate goes low, the out put will go low, if one of the gate is pulsing HI-LO, then the out put will be dictaed by that pin that is going HI-LO, the out put will follow that pin.

even the voltage would be replicated? because i'm getting 10V or more at all of the gates besides pin 10.
how do i check if i get signal at collector? probes collector to ground in ohms???

[petit]

Re: electromagnetic field therapy

looking at the diagram maybe the transistor is getting triggered, because if it wasnt, the speakers wouldn't be beeping????

[budm]

Re: electromagnetic field therapy

Meter in AC and measure right across E-C, or C and Ground. You should also be able to see DC at C and ground when it has not dirve signal, it will be close to 16V if the transistor is Off. Do not forget that you only has 700mV peak-to peak at B-E, if it is sine wave and your meter is true R.M.S, then the meter will display 248mV R.M.S. on the meter. 248mV RMS x 2.82 = .7V P-P

[petit]

Re: electromagnetic field therapy

Meter in AC and measure right across E-C, or C and Ground. You should also be able to see DC at C and ground when it has not dirve signal, it will be close to 16V if the transistor is Off. Do not forget that you only has 700mV peak-to peak at B-E, if it is sine wave and your meter is true R.M.S, then the meter will display 248mV R.M.S. on the meter. 248mV RMS x 2.82 = .7V P-P

even if emitter trace is coming directly from ground?

[budm]

Re: electromagnetic field therapy

Emitter is grounded (Common Emitter setup), so it does not matter. Just measure the C and Circuit ground or at the Emitter as the ground ref point.
You should Google how transistor works.

[petit]

Re: electromagnetic field therapy

Meter in AC and measure right across E-C, or C and Ground. You should also be able to see DC at C and ground when it has not dirve signal, it will be close to 16V if the transistor is Off. Do not forget that you only has 700mV peak-to peak at B-E, if it is sine wave and your meter is true R.M.S, then the meter will display 248mV R.M.S. on the meter. 248mV RMS x 2.82 = .7V P-P

i'm getting those 16VDC at collector, and frequency at lower setting 160Hz, next setting 320Hz, next 640 and at the higher setting 1280Hz ,same frequency as pin1.
also if i check pin bottom left of pulse transformer there is no signal there, the other three pins are collector, 15VDC and ground.
bad pulse transformer????

[budm]

Re: electromagnetic field therapy

That means the transistor is turing on and off, otherwise you will not be able to read the switching frequency. Youir diagram does not look right at all, pin 1 of the regulator is ground and filter caps C1, C2 positives are tied to ground and the negatives are ties to pin 2 Vin, that is reversed connections for the caps. the ANode of the SCR is also tied to ground and the area around transistor T1 Emitter are all grounded by the 4 dots on the diagram. That area does not look right at all.

[petit]

Re: electromagnetic field therapy

That means the transistor is turing on and off, otherwise you will not be able to read the switching frequency. Youir diagram does not look right at all, pin 1 of the regulator is ground and filter caps C1, C2 positives are tied to ground and the negatives are ties to pin 2 Vin, that is reversed connections for the caps. the ANode of the SCR is also tied to ground and the area around transistor T1 Emitter are all grounded by the 4 dots on the diagram. That area does not look right at all.

first time drawing one! yeah caps are wired wrong. Anode is going to ground (post 9 pic pemf 11) you can see the thick trace going up yo ground from anode, T1 emitter is grounded like that,let me double check


so we should think that pulse transformer is bad?

[budm]

Re: electromagnetic field therapy

One test you can try is to see if you can fire up the SCR to produce an output, just disconnect any component that is connected to the gate of the SCR, then solder in 100 Ohm 1/4w to the Gate, at another end of the resistor you will connect it on and off (make connection/break connection) to the Anode of the SCR. What we are trying to do is to pulse the Gate by connecting/disconnecting the Gate drive which will turn the SCR on and off, then you should see the LED that is connected to the Transducer blinking on and off.

[petit]

Re: electromagnetic field therapy

One test you can try is to see if you can fire up the SCR to produce an output, just disconnect any component that is connected to the gate of the SCR, then solder in 100 Ohm 1/4w to the Gate, at another end of the resistor you will connect it on and off (make connection/break connection) to the Anode of the SCR. What we are trying to do is to pulse the Gate by connecting/disconnecting the Gate drive which will turn the SCR on and off, then you should see the LED that is connected to the Transducer blinking on and off.

i did test the SCR with a flashlight like this guy http://www.instructables.com/id/SCR-...-a-Flashlight/ it got triggered but i did check the LED. Let me try your method to see if the LED turns on
Thank you

[budm]

Re: electromagnetic field therapy

If that section is working and you can see the LED flashes on (not sure if you do need to have the transducer connected or not for the LED to come on) then you can concentrate on the Gate drive circuits.

[petit]

Re: electromagnetic field therapy

i just checked the pulse transformer out of the circuit and i get 2.6ohm on each coil.
after checking the schematic, Transistor T1 is NPN, and it's backwards. emitter goes to ground and collector to anode of diode and pulse. in the diagram collector is wired o ground.
transformer

[redwire]

Re: electromagnetic field therapy

Check if the PCB trace from pin1 to the 2k7 resistor is ok. It's a long run and it might have a break. Otherwise it makes no sense to get voltage on the AND gate's output but nothing on the gate drive. The pulse transformer looks fine.
I noticed the AC mains is synchronized to the EMF pulse and if this was not working properly the SCR might not get triggered. There are many extra parts on the PCB as if the designer was still perfecting things. I would follow the diode from the power transformer on the far edge of the PCB's and see what the circuit looks like.

[petit]

Re: electromagnetic field therapy

Check if the PCB trace from pin1 to the 2k7 resistor is ok. It's a long run and it might have a break.

that trace is fine, i just test it.

I would follow the diode from the power transformer on the far edge of the PCB's and see what the circuit looks like.

i get stuck there drawing the diagram, there is a Single Op Amp TAB1453A that i cant find on EAGLECad

[petit]

Re: electromagnetic field therapy

schematic looks better now with voltages at transistor and pulse transformer

[petit]

Re: electromagnetic field therapy

i have run out of ideas
i dont get i pulse not even shorting Emitter-collector of that transistor... any idea?????

[budm]

Re: electromagnetic field therapy

You still did not try what I suggest in POST 150, the SCR will turn off once the current flow is at 0 amp crossing point of the sine wave even after you remove the gate trigger one the SCR is trigger on.

[petit]

Re: electromagnetic field therapy

You still did not try what I suggest in POST 150, the SCR will turn off once the current flow is at 0 amp crossing point of the sine wave even after you remove the gate trigger one the SCR is trigger on.

i just try that and nothing happened. 330 ohm resistor, one leg to gate and another to anode, what am i doing wrong? The SCR get triggered with the "Flashlight Tester"
Maybe the SCR is turning of before i can feel the pulse?

[petit]

Re: electromagnetic field therapy

i'm trying to understand how the pulses are being created in the secondary of the pulse transformer.
The pulse transformer has 2 windings 1-2 and 3-4.
I'm getting 16V at pin1, 16V at pin 2, same frequency at both as i switch the frequency knob. pin3 is ground and pin4 goes to gate
the pulse should happen when the transitor is triggered and pin1 is grounded trough Collector-Emitter?????
because there is no voltage between pin1-2 and i should be a pulsing voltage, am i right????