Re: gEDA-user: Power relay question

[Steven Michalske <smichalske@xxxxxxxxx>]

> Agreed. The majority of my parts come from curbside salvage, I've yet to
> find any programmers in the trash, but maybe someday I will?
>
I have found some in the trash.

For old Cypress chips, and I think some 8051s
But who needs programmers when chips have USB mass storage and RS-232
bootloaders.

My NXP LPC1114 programmer is a TTL level uart  and the chips aren't
terribly expensive.

> And my programming skills are weak. When I was in tech. school, the
> closest we came to programming was making LEDs blink with a Z-80 CPU,
> and some machine code.
>
> Since then I've managed to create (plagiarize and paste) some Basic
> programs, and I took and passed a PERL/CGI on-line course, a decade ago.
>
An Arduino is a very good starting point for working with Atmel AVR
systems and reasonable cost.

I also like the LPC1343 Quick start board from embedded artists, no
programmer the chip in bootloader mode is a USB mass storage drive.


> So my approach to this problem would have the latching relays, or an
> SCR/Triac solution.

Triacs are meant for AC systems and the kickback can keep them from
shutting off.  Triacs that are designed as snubberless are often back
to back SCRs.
SCRs will not shut off once triggered until the current goes to zero,
Same for TRIACs so tripping small limit switches won't turn off the
motors unless the switches block the current.

MOSFETs would probably be the best.

If your currents are low you could even use H-bridge mosfet chips to
drive each motor.
The TB6612FNG is a dual motor controller at 1.2 Amps average, 3.2A peak
The added benefit is that it is designed to cope with the kickback of motors.


Steve

>
> --
> Darryl Gibson N2DIY
> Linux, free software, for the people, by the people.
>
>
>
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