Trouble with high frequency astable multivibrator

[Exidor]

On second thought, I am pretty sure it would damage the pot. At 150 ohms, it would draw around 200 mA and there would be more than 1 watt across it.

 

[darth boozer]

As Vortector said, use a CMOS clock generator circuit. This can give you a tuneable frequency as well as easily providing the inverted and non-inverted signals to drive the power transistors. See "Clock Waveform Generators", about 1/3 down the page on the linked site.

https://www.electronics-tutorials.ws/waveforms/generators.html

 

[Exidor]

I have already ordered 2n3904's which should work. I am still not sure what power transistors would work well switching at 816.5 KHz. Wouldn't the 2n3904's hold up better than a CMOS chip in the vicinity of the Tesla secondary? Also, additional circuitry would be needed for the chip since I am running at 30V.

 

[rbelli1]

It is breadboarded.

Can you post a photo of the actual circuit?

BoB

 

[Exidor]

 

[Exidor]

 

[Tom.G]

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We expect to see some photos of the arcs out of that thing fairly soon.

 

[Exidor]

Here's hoping.

 

[Jp Tremblay]

I wanted to avoid inductors. I need a two phase square wave at 816.5 KHz. There would be high voltage around so I wanted to go with transistors instead of IC's. The output signals drive a transistor amplifier, which would feed the primary of a Tesla coil. I could use a CD4046 and an inverter, but the chips might get burnt out.

Hi maybe i missed something, but a regular push pull, using 2n2222a and it s conterpart 2n2907a can give good results at 1Mhz, as long you keep input resistor around 220 ohm or below if possible. In order to do so, you have to use 2 schotky diodes insteed, which greatly speeds up response time, installed between bases and collectors ( blocking sides toward + nodes, of course) such as MBR150. It drives fets satisfactory. Rise and fall time are about 25ns each (to 90%). Try this out ?

 

[Jp Tremblay]