Successful TPU-ECD replication !

[Earl]

Jason,

your FET driver circuit has a big error.  The manufacturer's spec sheet shows a test circuit which they use to determine the switching speeds.   They simulate the large FET input capacity by using a 1nF on the driver output.

In the real world, when you use this FET driver, you must remove this 1nF capacitor; the FET gate already has 1nF or 2nF capacity and you don't want to have an additional capacitance in the form of a 1nF capacitor!

As additional comments,

• the 4uF7 capacitor should be labeled tantal
• the 0uF1 capacitor should be marked ceramic
• it should be mentioned that additional parallel ceramic capacitors never hurt.  For example, additional 1nf and 10nF bypass capacitors.

Pay a lot of attention to the polarity of the tantal capacitor, if wrong polarity the tantal will catch fire and turn into a block of carbon.  Quite a spectacle.

Regards, Earl

Hello All,

I'm finally back from my weekend trip and thought I would take the time to draw up the the circuit diagram for my control circuit.

[z_p_e]

Hello all,

sorry I was a few days off line.

I saw the last video. A few comments:

1. there are 2 frequencies used and everything was OK. Then the 3. frequency added and nothing was OK!!!

When you use 3 frequencies, when you see that the 3rd frequency "disturbs" the other 2 frequencies then you MUST surch for better frequencies. The first 2 frequencies are NOT GOOD. You have to find a better frequency mix for your first 2 frequencies and then add the 3rd.

When all 3 frequencies are OK then you can swith off 1 frequency and the bulb shines NOT so bright as with all 3 of them. Then swith off 2 frequencies and the bulb is maybe only glowing.

In this case you know that all your 3 frequencies adds a littl power to the bulb. This is then the frequency mix you need.

This is then what I call a harmonic work off all 3 frequencies.

Otto

This is what I was thinking as well Otto...I agree. It does seem odd that the 3 frequencies would diminish the output, if adjusted properly.

Do you agree that the 3 frequencies should be harmonically related, and that the frequencies are fundamental, 1st harmonic, 2nd harmonic?

If so, I don't understand why no one is using the harmonic divider I designed, and then one only has to input one frequency. This will allow you to just sweep slowly from your chosen starting frequency, then adjust upwards for peak output power? 


Regards,
Darren

[gyulasun]

Hi Darren,

Sorry for chiming in,  the answer to your question is that you has to be always a little bit offtuned from the exact frequencies because the device may run away. (This was mentioned in one of Mannix earlier SM quotes.) 

So if the harmonic relationship holds and you start out from one single frequency and multiply them, the result harmonics will be right on spot when you hit the correct single frequency and this way you cannot make one or the other harmonic a bit offtuned, they will be right on spot too, creating the runaway situation.

Maybe your otherwise logical suggestion could still be used if the 12V power supply is greatly reduced or / and current limited / fused during the search for the right single frequency...

Gyula

[ronotte]

@Jason,

Earl is correct: remove the 1 nF condenser on Mosfet's Gate! It will only decrease the pulse rise-time in our case!   If I were you I'll remove the resistor either as it does not need except perhaps for safety rule.

Roberto

[z_p_e]

Gyula,

Indeed, using a lower supply voltage to start is an excellent suggestion, if one is really afraid of a "runaway" situation.

However, all 3 synchronized frequencies slightly off-tuned from the "big one" should also lower the output power.

Darren