My electronics is rusty

[Magnum]

Someone gave me the parts to make a flashing LED.

I need help with a couple of the parts.

One is a trimpot.

I have the schematic but don't understand how to hook it up.

The trimpot is 1M and it has 3 connections.

One connector goes to a 7555 chip.

Lemme scan this diagram and get back.

[Magnum]

http://yfrog.com/ccschematicj

For starters, I need help in determining how to hook up the trimpot.

[redskull]

potentiometers with three leads "go both ways"   :wink

You measure between one of the ends and the middle, and the other end will be the 'other part' of the total

e.g., if you measure .25M between the first and second, you would measure .75 between the second and third.  Measure .90m between first and second, and .10 between second and thirds.  First and third will always been the total 1M, regardless of position.

The way you hook it up depends on whether you want to 'increase' or 'decrease' as you turn clockwise.

-r

[Magnum]

I was told to set it to 500K before making adjustments.

I will post on the electronics group when the traffic dies down.

[dedndave]

some potentiometers are linear taper - some are not
audio taper pots are very common - they change value gradually at one end and rapidly at the other
without seeing the part you have, it's hard to say
with most trim-pots, the center lead is the wiper
if you get it hooked up and all the adjustment is at one end, you may want to try swapping ends
i.e. build it so that is easy to do   :U

that circuit is based on a 555 timer chip (well known as NE555, even though national semiconductor is no longer)
in the biz, we call em "triple nickels", and they are a dime a dozen   :bg

you can google NE555 and find all sorts of gadgets made based on that chip

they have low-power versions of that chip that would be well suited for what you want
i am not sure, but the 7555 may be a low-power version
the RC constants may vary for those versions

[Magnum]

Turn it to mid-rotation to get 500K. Use the center lead and either of
the ends. Ignore the one that's left... you don't need it.

John