How is the best way to take a 12 vdc input & reduce it to a 8 vdc output?

Question

I have a 12 vdc input and need to reduce it for use with a CCTV camera. The ac adapter provided which is 120 vac input & produces a 8 vdc 200 ma output. How is the best way to replace the adapter with 12 vdc input from the cars circuit? Thanks

Answer 1

I would use a 7808 Voltage Regulator.

It's a 3 leg device, that you put 12V into, and get 8V out. You will need to heat sink it, but it will easily supply 200mA.

Answer 2

Go with the voltage regulator. You need to have a resistor in series with the zener diode for the drop from 12 to 8 VDC, so you'll have to know what the exact current your camera uses to size the resistor correctly (too large will keep your zener from regulating, too small will melt the zener).

Adjustable three terminal regulators (link below) are much easier to work with. Calculate the resistors from a formula where you only need to know the input and output voltages and a current spec'd on the datasheet instead of having to know what your device draws.

Answer 3

flow with the voltage regulator. you're able to manage to favor to have a resistor in sequence with the zener diode for the drop from 12 to eight VDC, so that you'll could favor to be attentive to what the acceptable modern-day your digital digicam makes use of to length the resistor suitable (too large will keep your zener from regulating, too small will melt the zener). Adjustable 3 terminal regulators (link lower than) are plenty more suitable ordinary to artwork with. Calculate the resistors from a formula the position you in reality could favor to be attentive to the enter and output voltages and a modern-day spec'd on the datasheet fairly of getting to be attentive to what your gadget attracts.

Answer 4

You can purchase a Zener diode or voltage regulator chip of the proper size and put it in line with the 12 Vdc source. Just remember to add in a 10K Ohm dropping resistor behind it so you protect your zener.
I had this same problem when I tried to hook up a surveillance camera in a car and using the cigarette lighter as a source.