*Blue plastic "double" electrical box (for household wiring) $1
*Standard electrical outlet and outlet/switch faceplate $2
*12 volt transformer and full-wave bridge (cut up an old one that you are not using. $6 for Jameco #100095)
*Power cord (cut up an old one)
*558 timer chip (Jameco #27457) $1.20
*Solid state relay Kyotto KB20C02A (Jameco #175214) $6.55
*7808 or 7809 voltage regulator (Jameco #876352) $0.56
*two 100K pots (Jameco #29103) $2.18
*two 3,300 uF capacitors (Jameco #93666) $1.22
*PN2222 transistor (Jameco #178511) $0.12
*perf board, wire, maybe a 16-pin DIP socket, misc caps and resistors $2.00
Total parts cost is about $23. Here's a link to Jameco
Notes: My circuit provided times of about 1 to 6 minutes for the on and off periods. You may want to put a 10K resistor in-line with the 100K pots. If either pot is turned too far down, the circuit will stop oscillating, so the additional fixed resistance will prevent this from happening.This circuit does not provide the "soft start" that many commercial wavemakers tout. These motors likely use shaded poles for starting, and a soft-start controller would have to control the frequency of the AC power, not just the voltage. I find it pretty unlikely that this is what any wavemaker does, and for the price they charge, it's probably cheaper to buy a new powerhead every year! I haven't used my wavemaker long enough to know if it will kill the powerhead. I'm using an Aquaclear powerhead, and it clicks loudly upon startup, but there is no chatter. I may make another post about modifying the impeller to cope with the repeated startups.
I've experimented with using dimmers, current-limiters, etc, to control the speed of powerheads. The speed can only be reduced %10 or %20 before the motor stalls. It's not really practical without control over the frequency of the AC waveform.
The Solid-state relay in this circuit has a current limit of 2A. This mean it can control up to about 200W of powerhead.
Ben - This is too cool!
ReplyDeleteI recently got an Arduino kit to play with, and was thinking that making a wave maker might be a fun project. But since I do not have much experience with building electronics I was stuck on how to switch the pumps. I have seen examples of switching AC line voltage with relays, but the thought of a set of relays clicking on/off under my tank was not too exciting. I have not heard of Solid State Relays before, but it looks like the perfect component for this.
So since it has been a while since you posted this article, I am wondering how it is working for you?
Again Thanks - Mark
Hello, thanks for the comment. Yes, this wave maker circuit has been running 24hrs/day since I posted this blog entry. It has not had any problems.
ReplyDeleteYou can connect a pin from a 5-volt Arduino directly to the KB20C02A solid state relay -- no need for a transistor or current-limiting resistor.
Good luck! Let me know how your wave maker is coming along.
I was wondering if I would need the transistor/resistor, so thanks for the update. I will post an update once I get something working.
ReplyDeleteyou should make a youtube video, I have been searching for one and I still can find one. it latterly will pay to do it.
ReplyDelete