gear counter

[goldwing nut]

I need a circuit with two switches that will light 1 to 5 leds counting up with one switch and down with the other. the leds can be on one at a time or equal to the number of shifts. It,s to tell what gear my motorcycle is in.it will operate off the foot shifter.<p>[ August 31, 2004: Message edited by: goldwing nut ]</p>

[josmith]

Sounds like a job for a basic stamp. The only sticking point i can see is that your circuit would have to be syncronized to the gear you're in on startup. If you always start in neutral then it would be easier.

[haklesup]

how about a 4 bit up down counter connected to a 7 seg decoder (or a 4 to 16 line decoder). The shifter pedal would need two switches that would put the up/down pin at the correct logic level and pulse the clock pin.<p>There are several U/D counter chips in the 74xx and 40xx series with different features like edge/level triggered clock, reset/clear, binary/BCD etc. I think there may even be counters with decoders built in that can drive a display directly.<p>To avoid double clocking the counter when you shift (after all vibration and mechanical switches don't get along) you should debounce with a schmitt trigger and/or use an optical switch instead (look up "slotted optical switches" or sensors in DigiKey). Inductive or magnetic (hall-effect not reed-switch) pickup switches may also work well because they are sealed and will suffer the enviornment less. A good choice here will improve the reliability of your project greatly.<p>If you can sense the neutral position reliably and make a switch to reset the counter every time you go into N that may solve the re-synch problem. You can also hardwire a reset button on the dash so you can reset manually as required (probably want this in the prototype for debugging anyway)<p>Possibly as simple as 3 chips (counter, decoder, debounce logic), an LED display, switches, a handfull of R and C, breadboard and if you design for 12V operation (74HCxx or 40xx); no P/S (or just a 7805 regulator). Most things under $2, Could be as cheap as $10 total; thats way below a basic stamp and you probably have half of what you need already.

[dyarker]

Is the sequence 1 (half) N (half) 2 - 3 - 4 - 5 ?<p>That'll makes things a little more complicated.

[josmith]

The low price of logic chips make them look attractive but if you look at the big picture including the complex circuit board and all of the extra caps resistors etc to make it work it becomes a nightmare. The bs1 software is free, the programming cable can be made for around a buck. In this case it would be the stamp, five led's and their resistors and two switches. If it needs any tweaking you can re-program rather than re-build.

[Engineer1138]

I'll second josmith's suggestion, and go one step further: using a bare microcontroller (PIC in this case) chip is even cheaper than the BS1.<p>Here's a deal: since I was the one to start the "Build to order or swap" thread, I'll build you the circuit for the cost of parts + shipping (I estimate a total of about US$10 - $15) as long as you don't mind waiting up to a month for me to get around to building it The only restriction I'll ask is that you're not doing it for commercial gain: in that case I'll happily give free advice, but not free labor.<p>Go another step even further: we can write the project up as a Nuts&Volts article and include parts list & source code for the MCU so other people can build their own. I wrote an article on motor control for N&V years ago and have been feeling the itch to write some more.<p>
ps,
Does anyone know if there's a way to preview your posts before you hit "Add Reply?"<p> <blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by josmith:
The low price of logic chips make them look attractive but if you look at the big picture including the complex circuit board and all of the extra caps resistors etc to make it work it becomes a nightmare. The bs1 software is free, the programming cable can be made for around a buck. In this case it would be the stamp, five led's and their resistors and two switches. If it needs any tweaking you can re-program rather than re-build.<hr></blockquote>

[goldwing nut]

I really like the idea of engineer 1138. since I know almost nothing about stamps or pics. This does sound like the best way to go from my point of view. Time is not of the essence and I like the idea of having input in an article and learning something new. Get in touch.