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Unanswered Questions





AQUABOT Pool Cleaner June 2017

A friend of mind asked me if I could fix her “PoolRover” pool sweeper. The timer does not work properly.

The power supply/controller has a big transformer and circuit board inside, and for a lack of ID, has a bar code P12909124848. I have looked high and low for a schematic for this unit, both with the manufacturer and on the Internet, but have come up blank. I started working on a start/stop timer from [url=http://ronj.eu5.org/rt2.html]http://ronj.eu5.org/rt2.html[/url].

Does anyone have any better solutions? Timer on for 30 seconds and off for two seconds, and back on again.

#6175
Terry Arnall
Hayward, CA


Ni-Metal Hydride Battery Chargers April 2017

Now that Ni-Cad batteries are becoming an endangered species, is there any way to convert their chargers to work on the newer and ecologically sounder Ni-Metal Hydride batteries? I read that the Ni-Metal batteries have very different charging requirements rather than the constant current chargers for Ni-Cads. I have several bench chargers, not to mention a multitude of “wall warts” that I would like to modify.

#4171
Michael Herman
La Quinta, CA


Surround Sound Questions March 2017

I recently upgraded from an older two-channel stereo system to a 5.1 surround sound receiver. I have left, right, center, and sub woofer speakers set up at the front of the room, but no easy way to run wire for the rear speakers.

What’s the best DIY wireless method to get my surround sound to the back of the room?

Does someone have a schematic for a stereo transmitter/receiver that I could build? Would using a combination wired and wireless setup  have any issues with syncing the front and rear channels?

#3174
Dustin Quintanilla
San Luis Obispo, CA


Three-Way LED Flasher February 2017

I need a simple circuit to sequentially flash three separate strings of 10 LED lights. Flashing two strings is easy; three is tougher.

#2173
Michael Herman
La Quinta, CA


Auto Bell Galloping Dominoes February 2017

I have an electro-mechanical gambling machine — Galloping Dominoes — from the company Auto Bell, and would greatly appreciate if someone could direct me to where I could find a schematic. It has a motor that turns four large switch cams and three smaller cams, and has numerous multi-pole relays all interconnected. Thanks!

#2171
Randy Grunwell
Suwanee, GA


Pool Bot Timer June 2016

My pool bot timer quit. The transformer is good but the timer is not. I would like to build a timer to switch a relay off and back on every 15 seconds and/or 30 seconds.

#6161
Terry Arnall
Hayward, CA


68HC11 To DS1302 RTC February 2016

I recently purchased what some would consider a dinosaur when it comes to microcontrollers: a 68HC11. I purchased it at an estate sale because it was one I used while attending school. My question is where can I find info on creating a program that would allow me to interface the SPI to a DS1302 RTC?

#2162
Michael Bennett
Kankakee, IL


Motor Brake December 2015

I’m looking for a schematic for an electronic brake for a one phase 120 VAC motor. I had a commercial one, but it failed. I discovered it was potted with no way to tell what was inside.

#12152
George Gray
via email


Servo Cycler August 2015

I would like to make a servo tester that would continuously run a servo from 0 to 180 degrees and back. I have found a number of 555 servo tester designs, but none that actually cycle the servo. Does anyone have a schematic for such a thing?

#8153
Owen Corlis
Plymouth, MI


TV Headphone Amp July 2015

I listen to TV at night using headphones. I have noticed that the volume level that can be produced by the TV set is actually too low for me to clearly make out the dialog. Is there a booster amp that has a tone control that I could use between the TV and my headphones to make the sound louder and clearer? I would like to build this myself so a schematic would be appreciated.

#7153
Zachary Mailey
Palmdale, CA

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