# Transistor Astable Multivibrator Circuit

Discussion in 'The Projects Forum' started by pafrazier, Nov 4, 2013.

1. ### pafrazier Thread Starter Active Member

Jun 4, 2011
57
0
HI,

I want to construct a high frequency low power Transistor Astable Multivibrator. I posted some time ago and someone recommended the 2N2369 - SWITCHING TRANS, NPN, 15V, TO-18. I know the formulas to use in the calculations. I am switching a load on and off across a capacitor. I just want to do that at the highest frequency that I can. I want to use the lowest possible power to run the astable multivibrator circuit and achieve the highest frequency switching. The capacitor and load part will be low power as well. It will be designed to stay within the parameters of the transistor above. My question, what is the best approach in designing the circuit? Is there any advice on how to achieve my goal stated above.

Thanks

2. ### Shagas Active Member

May 13, 2013
802
74
As far as I know , transistors take a while to go into saturation so if you make it so they stay in active mode you should be able to achieve a higher frequency .
I hope someone more experienced has something to add to that.

3. ### THE_RB AAC Fanatic!

Feb 11, 2008
5,435
1,305
I'm not sure about "more experienced" but it looks like he is asking about using a multivibrator to "achieve the highest frequency switching".

Generally single transistor oscillators are used for high frequencies. We REALLY need to know the desired frequency, as that will determine the best type of oscillator.

4. ### pafrazier Thread Starter Active Member

Jun 4, 2011
57
0
Hi,

The rated frequency for the stated transistor is 500 mhz. Is it possible to achieve a 500 MHz pulse with an astable multivibrator circuit? I will be using the AMC as a pulse generator and use the same transistor as stated above to switch a load across a capacitor. I looked at the 555 timer pulse generator that is only rated for 1 mhz. I am trying to balance switching speed with power consumption. Can you suggest any other pulse generator circuits that can achieve 500 MHz? Or what are the limits you can achieve with any pulse generating circuit?

Thanks

Dec 20, 2010
129
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6. ### pafrazier Thread Starter Active Member

Jun 4, 2011
57
0
Hi,

I posted a while back about using the rf transistors for switching. However I was was told that they were not suited for switching purposes and the 2N2369 was recommended.

Thanks