Quote:
Originally Posted by Alpinestarhero
.. Embee, I think I understand what you're on about, but im not completly certain...maybe you can PM me with what you mean in a more numpty-friendly langauge? ....
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I'll post something here, others with more electronickery knowledge can add/correct/expand as necessary.
The Maplins "speed controller" is just a variable mark-space device, in other words it switches the output on and off rapidly for varying proportions of time, the output is at full supply voltage when it's on. I don't know what frequency it runs at, for a simple resistive load like heated grips it doesn't matter, but it's often in the kHz range. The relative proportion of on/off is termed the duty cycle (usually in percentage terms. e.g. 50%) or mark-space ratio or similar, the "on" pulse width is "modulated", hence the term "pulse width modulated" or PWM.
In this manner it controls the power the device gets supplied with, it doesn't rely on "wasting" energy in order to do it.
You'd need to measure the resistance (or current demand) of the grips to decide whether it would be adequate.
The current rating of this unit is probably determined by the output device, and I guess it could be uprated by either substituting a larger device (transistor/thyristor?) or using it as it stands to drive an additional one. This is where my knowledge runs dry I'm afraid.
If you are adept at wielding a smouldering iron you could probably rig the control pot remotely from the board, making it neater and possibly improving weatherproofing.
It'll probably be cheaper/easier to buy a purpose made unit, the better ones will be this type of control circuit anyway.