Delta Pulse

[hawk17966]

What 24v ...?

:confused:
What 24 volts are you talking about Carl? D.Pulse uses only one 12v accu.
same as Pulse Star II....
Sory if i bug you, but my DP is working average,i would like to improve it if it is possible....
Thanks

[Carl-NC]

I don't know about the PSII... maybe the coil only sees 12V, not 24V... maybe the pulse width is shorter.

Use whatever resistor value keeps the coil+resistor above 6 ohms. Also heat sink your FET.

[hawk17966]

Many thanks!


Many thanks Carl!
It will help me.
In PS II i noticed that there is no any heat sink on fet? Coil resistance as i said before is 2 ohms...About resistor i am not shure of proper value..
In delta Pulse pretty simillar but coil shoul nod be under 6 ohm....because than fet is warm,hot even blows...!?
As you see i am not expert in those things...i would like to learn more and understand more, but since do not have some elementar knowldege....."tech-language" sometimes confuses me.....

[Carl-NC]

You need to be careful with power, and it's not straightforward in a pulsed circuit. Looks like the coil gets a full 24V, so let's say we run 150Hz (T=6.7ms), a 4 ohm coil, and a 335us pulse width (5%). The IRF740 has 0.55 ohms of R-on, so during turn-on it sees 2.9V and 5.3A. This is 15.37 watts, but only for 5% of the time. For the remainder, the FET is off, so the time-averaged power will be 770mW. This should not be a problem, but only if during the OFF time there is sufficient heat sinking to keep the FET cool. If not, then the temperature will rapidly climb toward the 15 watt level, and possibly blow the device.

You can do the same calculations for a series resistor, and probably find that you need at least 1W, probably with heat sinking.

[hawk17966]

Thank you!


Thank You, Carl!

But still not clear; can i use lower resistance coil than without risk to warm fet or even get it hot and blow?

"To reduce coil current, you need to add a few ohms of resistance in series with the coil."
That resistance should be resistor but high power (5w,10w) or 1/8w or simillar? Or does'nt matter?

Pulse Star II machine used with coil 2 ohm resistance and high power in it does'nt blow fet, but Delta Pulse even with 3-4ohm coil a less power blows fet?? How come? Even freqency is lower (150Hz) than at PSII...???!!!
:confused:

[Carl-NC]

I can replace TL071 by TL081 ?????

Yes.

Can anybody explain me in details role of dumper resistor in this PI design?
How it affects on fet and coil?
How can i use less resistance coil(ex.2ohm or 3 ohm) without blowing up fet.
As somebody mentioned here, if coil has resistance less than 6-7 ohms than fet is getting very hot. Can dumper resistor help somehow?

The damping resistor dampens the exponential decay of the inductor. Without it, the inductor will ring. It does not affect coil current (to any extent). To reduce coil current, you need to add a few ohms of resistance in series with the coil.

- Carl

[hawk17966]

Dumper resistor?


Hi! I need help!
Can anybody explain me in details role of dumper resistor in this PI design?
How it affects on fet and coil?
How can i use less resistance coil(ex.2ohm or 3 ohm) without blowing up fet.
As somebody mentioned here, if coil has resistance less than 6-7 ohms than fet is getting very hot. Can dumper resistor help somehow?

[diminute]

OK

I can replace TL071 by TL081 ?????


Thank

[diminute]

So good

Sorry for my bad english

Yes, is replace the TL062 by the TL072... I have this second op.

You said that 071 replace the LF357, I don't have 071 now but i have four TL081, is the same ??? I found that TL071 is aproximaty igual to TL081, with the only diferrence of it's Offset Current, but in the circuit of DPulse this parameter is not important.

TL081 = TL071 ?????

Thank

[Mrand]

I was speaking for the Frontend OPAmp. He is working in the characteristic configuration ( "common +" ). They want only few OPAmps to work correctly. NE5534 and LM318 are very good (318 is faster but has some bigger noises). Unfortunately they aren't suitable for applying to this circuit.
Mrand

[Geo]

According to my experiments only LF357, LF356 and TL071 are working goodly at this configuration . Unfortunately NE5534 isn't suitable for Delta Pulse or Sniffer.
Mrand

Hi Mrand. At Delta Pulse D5 is TL062 and at XR71 is TL072. I tried both without difference. Now i use TL072. So i believe that Diminute can replace TL062 with TL072.
Best Regards

[Geo]

Hi. Schematics of Delta Pulse are OK. Try it.

[diminute]

ok

Les estoy muy agradecido, espero tener exito en mi nuevo proyecto... estoy seguro que con la ayuda de ustedes voy a lograrlo.

He oido decir que el esquema del Deltha Pulse presenta errores, es cierto o falso ???? yo tengo dos esquemas pero los veo iguales... creo que están en este mismo hilo del forum.


Saludos

diminute

English (Google)

Very I am been thankful them, I hope to be successful in my new project… I am sure that with the aid of you I am going to obtain it.

I have heard say that the scheme of the Deltha Pulse presents/displays errors, is certain or false? I have two schemes but I see them equal…

I believe that they are in this same thread of the forum.

Greetings

diminute

[Mrand]

According to my experiments only LF357, LF356 and TL071 are working goodly at this configuration . Unfortunately NE5534 isn't suitable for Delta Pulse or Sniffer.
Mrand

[Geo]

In the Deltha Pulse I can replace:

1 - LF 357 by LM318P or NE5534 ????
2 - TL062 by TL072 ???
3 - BC 546 by BC 548 ???
3 - BC 557 by BC 558 ???

Please awnser me these questions, and thank...

What's is the final version of Deltha Pulse (schematics) ???

You can replace transistors and TL062 but don't replace the LF357. If you want to experiment then try to connect pins for thermal offset and make bigger gain (replace R17):confused: . If you can not find the LF 357 then try NE5534 but not the LM318. I tried it without results. Maybe there was problem with IC ... i don't know.
As i know there is only one schematic for D.P.