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Help with control circuit


New Member
I have an existing board that I had designed for me that controls motorized displays and music in a clock. It uses 4 ics (lm324n op amp, 74hct4040 logic counter, 74hct flip flop and a 555 timer). I don't have a schematic of the circuit, but I have posted a picture explaining the connects.

The operation is as follows: the clock chimes and counts the hour which is monitored though wires from the electronic clock speaker. After a short delay, the left and right animation motors are powered for a time (controlled by a pot). A relay is energized that turns on an electro mechanical device that starts a mechanical music movement. The circuit resets until the next chime hour. There is a override button to test operation between chimes. The supply voltage is 6vdc from a wall transformer. The motors are display (hankscraft) type and draw low amperage.

This is a prototype I was going to use in floor and mantle clocks that I build.
This circuit board was too expensive to build ( although it 's been working in my prototype floor clock for 15 years) In recent years, there has been a few new things that I would like to try , like an Arduino controller. The gearmotor technology is miniaturized to the point where I have designed a small enough electro mech. actuator that could fit into my mantle clock. Also I would like to interface with sound files, led lighting. I have installed the new led light strips in my floor clock recently.

I would like some help with the circuit design and arduino program (sketch). I would like to ultimately produce a circuit board that I can use the atmega chip. I am not an electronic techie so
any help would greatly be appreciated!



Well-Known Member
How much is "too expensive to build"? JLCPCB's SMT assembly service is incredibly cheap. If your existing board was converted to a surface mount design, I'm guessing that 10 boards delivered to you would be about $70 total, including shipping. That's $7 per board, and it would be much smaller than the existing board.

There are a couple limitations for what you can do for this cheap assembly service:

> The components must be in JLC's assembly library and in stock at JLC. This shouldn't be a problem for any of the parts on this board.

> Only surface mount parts will be assembled to the board. Any through-hole parts will have to be soldered separately. This would probably be terminal blocks on this board, which are easy enough to solder.

If the existing design works well and you have a schematic, this might be a good approach.


Well-Known Member
Most Helpful Member
If he populates the boards himself with through-hole parts, he can get 10 - 4" x 4" boards for under $15 delivered.


Well-Known Member
Most Helpful Member
I suggest you get an Arduino (Uno will do) and an L298N dual H-Bridge controller. Looking at banggood, you can get both for less than $10. Try to control the motors with the arduino - example page. Also, try powering the arduino from the 6V supply and use a largish (2k-5k) resistor from one side of the speaker to an input pin to see if you can detect the chime starting - if not detected, try the other speaker terminal..


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