Multimeter Clock
5 Steps
The Multimeter Clock consists of three multimeters, the first meter displays hours, the second displays minutes and the last displays seconds. A 16F628A PIC microcontroller keeps track of time and outputs a calculated current to each meter to display the current time.

Get your own Multimeter Clock Kit here.
See Multimeter Clock project page here.

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## Step 1: How it Works

The user enters the time by pressing three time adjust buttons. The first button increments the hours, the second button increments the minutes and the third button resets the seconds. Once the time has been entered the microcontroller will keep track of time from there. An interrupt fires every 10th of a second to increment a 10th second counter. Another routine checks to see if we have at least one full second of time, if we do the current time is incremented by a second.

The microcontroller has a separate output for each of the three meters. The meters are all in 0.5 DCmA mode, the negative lead of each meter is grounded and the positive leads are connected to a microcontroller output via a current limiting resistor. The resistor in this case is a 4.7K however this can be adjusted depending on the meter current scale available. Keep in mind that the PIC can deliver a maximum of 25mA to each meter so a meter with a lowest setting above 25mA would not work without additional circuitry.
mikerosati says: Oct 24, 2012. 5:15 PM
Great idea - I'm going to give this one a go as well..
I second in asking what software was used to draw up the schematic..
taylorglenn says: Aug 21, 2012. 3:59 PM
What software did you use to draw this schematic?
ynze says: Jun 28, 2012. 2:50 AM
Owww, wonderful idea, great build! Thumbs up!
WhiteTech says: Jun 18, 2012. 7:34 PM
Hey, Excuse the noobish question, but your setting is .5 mA, so the max, when it's set on it, is .5 mA showing on the scale?

I have access to ammeters that have a non-changible scale that goes to 20 mA, can the kit run this?
Toastalicious says: Aug 16, 2010. 11:11 AM
Why does the first meter say sunMa while the others are sunWa?
Wroger-Wroger says: Jun 3, 2012. 1:07 AM
What? You have never made a mistake either?
abbtech (author) says: Jun 2, 2012. 7:36 PM
LOL, I never noticed that before. I am thinking that the 2nd and 3rd are SunMa knockoffs. :)
abbtech (author) says: Aug 16, 2010. 12:10 PM
LOL. I never noticed that before! That represents the quality of these meters I got, I should have spent more money on them. :)
Kasm279 says: Aug 18, 2010. 1:47 PM
I have one just like it except the colors around the dial are white, green, and red. Also, mine says MODEL instead of Sun(W/M)A, but it does say "YX-1000A" on it...
signalelektronik says: Aug 16, 2011. 8:05 AM
What a great idee!
abbtech (author) says: Aug 16, 2011. 9:38 AM
Thanks
Dr.Bill says: Aug 29, 2010. 4:24 AM
this is too cool
cdousley says: Aug 17, 2010. 6:47 PM
LOVE IT!
abbtech (author) says: Aug 17, 2010. 7:16 PM
Thanks for the comment. Glad you liked it.
canida says: Aug 16, 2010. 5:11 PM
Nice project! Excellent work.
abbtech (author) says: Aug 16, 2010. 6:23 PM
Thanks. :)
twocvbloke says: Aug 16, 2010. 8:21 AM
That's a pretty cool device, I'm sure the steampunk sorts would love to make a version of it somehow, but as it is, I like it... :)