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Originally Posted by Alan Anderson
Agreed. Those circumstances might even be applicable to what rbmj (the original poster) is trying to do. He specifically asked about exactly what you suggested, but he quite properly recognized that such a scheme would not be using a speed controller.
The usual meaning of "motor speed controller" in this context is something which takes a hobby servo control signal and provides a suitable modulated and polarity-switched output. Using a solid-state relay is a lot like using raw transistors; you need to provide your own PWM. And you're not going to be able to control the motor direction with one.
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I absolutely agree. I don't think he ever made it clear that the needs to go both forward and reverse from the input (he could just use more solid state relays or a reversing clutch...etc), or even what kind of motor, but if he does obviously your point is quite valid.
The other point taken as well, normally you'd expect your electronic speed/motor controller to operate on the input signal and condition the result for the output. Perhaps even give you some features like thermal protection.
Still without more detail we don't know what's expected. Several of those R/C speed controls will differ slightly in how they react as well.
Additionally I've assumed again he needs to drive a DC brush motor. I hope that the difference between that and a DC brushless motor has been realized. These two kinds of motor are rarely interchangeable unless the controller for the brushless motor is part of the motor.
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Brian, I encourage you to slow down a bit and let some of the information you're reading sink in and get sorted out before you repeat it. Innovation FIRST hasn't sold that product for a great many years, and actually doesn't sell any of the products listed on the ifirobotics.com catalog pages anymore. Those pages are no longer accessible from the IFI home page. If you manage to find one by some other means, they all have that prominent red text at the top explaining that the Innovation First products are now sold by VEX Robotics under the VEX PRO brand. That solid-state relay module is not one of the products which made the transition.
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Fair enough. I saw that it linked over. The point was more that I suspect the initial confusion of the Wikipedia author originated in the availability of this item. It does not appear to me that Innovation FIRST ever actually called it a Spike relay. Perhaps you know better on that point.
I'm almost positive that this confusion is not new either. I recall vaguely a previous topic in these forums with a similar issue Spike relay related issue. Sorry didn't mean to step in the same mess again.