i have a digital voltage display ( does 0-200v) for my car, it needs a input power of 5v 80mA though... anyone know how to wire this? relay? resistor?

 

Go to an electronics shop and get a 12v-5v voltage regulator and wire it up through that.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Xsi &raquo;</TD></TR><TR><TD CLASS="quote">Go to an electronics shop and get a 12v-5v voltage regulator and wire it up through that.</TD></TR></TABLE>

sounds about right.

 

what like a radioshack? i went there they had nothing useful except a $22 ac adapter that was 5v

 

Ok, I live in New Zealand so I'm not sure what shop you should go to but the thing I'm talking about is tiny (about 1.5cm long and 8mm wide) and is usually in those little plastic trays with about 50 other ones.

 

I would use a resistor but a voltage regulator might be a good idea for a novice.

http://www.radioshack.com/prod...-1778 is the radio shack part that will work. They should also have non-adjustable regulators that have a 5V output. There is no datasheet listed so I can't calculate junction temperature for you.

It doesn't neccassarily have to be 12-5V as long as the output is either adjustable or fixed to 5V you will be fine. I think the one at radioshack excepts up to a 35V input.

 

i thought of a resistor too, i know of them, i used them on l.e.d.s in my car, but i dont know which to get for this, and the guy at radioshack said there isint one that would drop 12v to 5v....

 

I see, the guy at radio shack is a moron.

You would need to know if your display used a continuous 80mA this is what is really important if you were to use a resistor.

Buy the voltage regulator and I will tell you how to hook it up.

If your display uses a continuous 80mA you possibly could use a 113 ohm 1 watt resistor. Which would work at 14 volts but not 12V, your display would go dim thus the purpose of a regulator. Please don't use a resistor, it requires a deeper knowledge of the circuit.


Modified by nsxxtreme at 9:47 AM 7/29/2004

 

http://www.radioshack.com/prod...-1778 would this do the trick?

 

Yes

http://www.national.com/ds/LM/LM117.pdf is the datasheet for it.

with what your running the part should heat up 25 degrees above ambient. So you should be fine without a heatsink.


Modified by nsxxtreme at 12:48 PM 7/29/2004

 

cool, thanks

i'll go grab one.

 

also buy a 5 volt zenor diode and a 1/4W 1k ohm resistor

 

these look right?


how do i wire this ?

thanks


Modified by fuctup at 8:37 PM 7/29/2004