H-Bridge kit

[blackjames]

hi,
Over the past two weeks i have been designing a 20A h-bridge kit based on basic through-hole soldering with dimensions of 50x45mm. i'm wondering if this kit would sell for about $20 australian. it costs about $5-$7 parts including esd safe bags. pcbs cost about the same ($5-$7 AUS). please give some input as this is my first attempt at selling an electronics kit.

[Psi]

need more specs, voltage, max frequency etc.
but $20 doesn't sound expensive

[blackjames]

heres some more information:
based on irf540 and irf9540 mosfets in to-220 packages.
rated to 40volts max. control voltages are anywhere from 5-15V.
suitable for arduino control interface

[blackjames]

i haven't had a prototype pcb made up yet, because i dont want to waste money on something that wont sell. im also currently designing a inter-face board with a opto-isolated input. it takes a high or low input and spits out 2 signals, one for each side of the h-bridge. dose it sound like a good idea?  

[Kremmen]

Depends. The price is not bad but what i would like to see are the use cases where this would be applied. That and the specs. After all that is how the prospective buyers will evaluate your kit. Now i have a pretty good idea where a H-bridge might be applied but what was yours?

[blackjames]

my application is for a robot rc car hack thing, controlled by an arduino. what do you think?

[Kremmen]

I have no idea of the potential market for such things but at least the price seems reasonable for the specs. Just make sure that the shield is usable from Arduino right away i.e. either by the regular Arduino analogWrite (pwmout) or a dedicated library freely downloadable from somewhere.

[blackjames]

one thing, it is just  a square pcb, not and arduino shield. it has places to solder wires or pcb mount screw terminals.

[Kremmen]

Then it is not specifically an Arduino shield and you cannot market or brand it as an Arduino component. Whether this is a good or a bad thing is another matter, but giving the impression that it is an "Arduino component" immediately creates the expectation that it is a directly pluggable shield. If it is not you need to manage the expectations of the buyers by making this very clear and at the same time you must have a solution how the board connects to an Arduino. You just cannot leave it open and at the same time say it is an Arduino compatible component.