555 Timer Oscillator

555 Timer Oscillator

A voltage-controlled oscillator (VCO) using the timer 555 is shown in figure.

 

The circuit is sometimes called a voltage-to-frequency converter because the output frequency can be changed by changing the input voltage.

As discussed in previous blog posts, pin 5 terminal is voltage control terminal and its function is  to control the threshold and trigger levels. Normally, the control voltage is ++2/3V_CC because of the internal voltage divider. However, an external voltage can be applied to this terminal directly or through a pot, as illustrated in figure, and by adjusting the pot, control voltage can be varied. Voltage across the timing capacitor is depicted in figure, which varies between +V_control and ½ V_control. If control voltage is increased, the capacitor takes a longer to charge and discharge; the frequency, therefore, decreases. Thus the fre­quency can be changed by changing the control volt­age. Incidentally, the control voltage may be made available through a pot, or it may be output of a transistor circuit, op-amp, or some other device.

Thank you

 

12v Regulator Schematic (15A)

12v Regulator Schematic (15A)

 Well I dont know much about electronics so I asked a friend of mine to make me a 12v regulator. Please do not ask me about it since I have no idea about those kind of things. However, I wasn't able to find a decent schematic of a 12v regulator so here it is. The Voltage on the car must be over 12.8 to supply a regulated 12V but the nice thing is that it is 15A and with a fuse can be lowered to 5A. He said that the components are cheap and not hard to find. He uses a so called "zener" which I havent got any idea what it is!

I am interested in your comments since you know more about this stuff. I know this isnt the BEST regulator available but it is a simple solution that I wanted to find and never did. Hope that it will be usefull to you all.

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 Thank you