539Views7Replies

Author Options:

Modding a clock to run at half speed (resolved) Answered

Picture of

I want to make a clock that runs at half speed, or atleast is slowed down.
Is this possible to make with resistors or do I need to make twice as large gears to make it slow?

Obviously, the first idea is to prefer over the ladder.

I've managed to get my hands on the circuit board that produces the hertz pulse, and also a blueprint that shows that if you put a 1k resistor on the input, it still beats at 1hz. Should you maybe put a resistor on the other end, the output? And how big of a resistance should I use?

(It also shows two diods, which are added, which is used to light up a LED)
Pictures from JosePino

I appreciate the help, thanks!

RESOLVED: http://www.youtube.com/watch?v=BMtoBKAzhgA

7 Replies

user
isudoru (author)2007-05-04

Actually, I resolved it like this.

I opened the back, as image depicts, and then I took the smallest gear, the one that is attached to the magnet (that twirls on the pulse from the electromagnet) and cut away all the tooths but one.

Since the gear spins jerky and quite uncontrolled on cheap clocks, it wont actually be precisely half speed, unless you place it at a certain angle - which is found by trial and error.

The simplest solution turned out to be the quickest.

Thanks for all the help! :D

Select as Best AnswerUndo Best Answer

user
frank26080115 (author)2007-05-03

get a crystal with half the frequency

Select as Best AnswerUndo Best Answer

user

fine, if that won't work, how about this, use a 555 timer circuit to either replace the crystal itself, OR, use it to trigger a mosfet switch to power to the clock 555 timers can be used as oscillator replacements right?

Select as Best AnswerUndo Best Answer

user
trialex (author)frank260801152007-05-03

Actually that's interesting. You can't get 16.XXX kHz crystal (ie half a 32.XXX kHz, which the one above almost certainly is) - not that I've found anyways. Not knowing very much about cystals at all, what would happen if you put a crystal in parallel with the first one? What about if you put it in series? My guess would be that they would both do nothing, but it'd be interesting to find out...

Select as Best AnswerUndo Best Answer

user
westfw (author)frank260801152007-05-03

This would probably work, but... The crystals are usually 32768Hz, which is a convenient standard (215 Hz), and I don't think I've ever seen a 16384kHz crystal. If you really have 3-5V instead of the usual singe AA cell found in most clocks you could drop in a small microcontroller programmed to produce the correct waveforms. (I believe that to drive the clock motor, the output pins alternate polarity...)

Select as Best AnswerUndo Best Answer

user
LasVegas (author)2007-05-03

You could do this in one of two ways. One, replace the crystal with a hard to find (not impossible) 16384kHz crystal. Second, add a D-Type flip-flop to the output to act as a frequency divider.

The second technique would be the easiest to implement. Just use a 4013 CMOS (will run with the 3-5v source) using this technique.

Select as Best AnswerUndo Best Answer

user
lemonie (author)2007-05-03

Maybe it's the capacitor you need to change?

Select as Best AnswerUndo Best Answer