Steven Marks secret

[nvisser]

This is the ic Iuse. TL494
Duty cycle adjust and risetime of 100nsec
Here is a 12k low quality picture of the circuit

[otto]

@nvisser

give us something with a 555 if possible. There will be a lot of blown oscillators until we finish our job.

In the beginning I have blown only MOSFETs, a lot of them, now as Im "cleverer", Im blowing oscillators. This is ....

Otto

[nvisser]

Here is a better picture used by JL naudin on the meg
The idea of this post is to show how he used the TL494 as oscilator

[nvisser]

The 555 are realy outdated and the tl494 cost about nothing and is easier to built. You can adjust the duty cycly by changing the voltage on pin4 between 0 and 3.3v with a voltage divider ( resistor and pot) or with a 3.6v zener, 820 ohm resistor and 2k pot like in my first drawing
The problem with the 555 circuits is that when you adjust the duty cycle you also change the frequency. Very annoying!
On the TL494 ,Pins 9 and 10 give you opposite outputs as in JL Naudins circuit or if you use it it as in the first drawing you connect 8 and 11 together as output and use a 1k pullup resistor to 12v. Pin 9 and 12 than connect to ground
You should really use mosfet drivers like mc 33151 or Tc4420. It will switch your mosfets fully on and also switch very quick which prevents overheating of fets

[rensseak]

@nvisser

give us something with a 555 if possible. There will be a lot of blown oscillators until we finish our job.

In the beginning I have blown only MOSFETs, a lot of them, now as Im "cleverer", Im blowing oscillators. This is ....

Otto

Hello Otto,

this is the one i will use for my oscillators for testing

http://www.hobby-bastelecke.de/bilder/schaltungen/rechteckgenerator3.gif

later i thing this will be the small solution.

http://www.hobby-bastelecke.de/bilder/schaltungen/rechteckgenerator1.gif

the site where i found it:

http://www.hobby-bastelecke.de/projekte/signalgenerator_rechteck.htm

Norbert