# How to self start a MOSFET multivibrator circuit

I have built a simple multivibrator circuit using IRF530s for the switchers. It does not start unless I introduce noise by touching one of the timing caps. I tried to include a circuit image but as a new user could not. It is a textbook multivibrator only using power MOSFET instead of Bipolar Transistors. How can I make this circuit start at power up?

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If you provide a link to the image, we'll edit it into the question. –  Dave Tweed Jan 10 '13 at 17:00
You can see the circuit at: circuitlab.com/cs56fxj3 I have tried different timing values and voltage supplies. Both in the simulation and in the lab the circuit will not self start, but always starts with just a small touch of my finger. –  user17689 Jan 10 '13 at 17:52
–  user17689 Jan 10 '13 at 18:02
@user17689 How does one execute a small touch of the finger on the circuit sim? :-) –  Anindo Ghosh Jan 10 '13 at 18:14
no time to write an answer, but see virtual.cvut.cz/dyn/examples/examples/electronic/mosmulti/… –  Phil Frost Jan 10 '13 at 19:25

2. In your simulation, the circuit will have trouble starting up because it is exactly symmetrical. Disturb the symmetry (e.g. by making R3 = 1 k$\Omega$ and R4 = 1.001 k$\Omega$), and it may start. A real circut will have enough imperfections to start, no need to buy a 1.001 k$\Omega$ resistor in Schillicon Valley.