DIY Cruise Control on 07-08 Yaris (step by step)

[CTScott]

Originally Posted by scape

quick question on those momentary switches: I found a few at radioshack but they are low-amp rated (like .5A).. I noticed the referenced digikey switches are around 3 amps. what's the max rated amperage I should shoot for?

i found a few packs of resistors at the local radioshack, but none at 240. looks like i'll be soldering them together to make 240. they're rated at 5% tolerance, if combining them would the tolerance inherently go up?

Any momentary switch is fine. You are switching an analog input to a microcontroller, so the current is negligible.

For the resistors the tolerance means how far they can be off, so a 100 ohm, 5% can be 95 to 105 ohms. Since it is a plus or minus rating, chaining them together means that they can cancel each other out, or add to the percentage off in either direction. If you have a multimeter, you can measure the actual resistance of each.

[scape]

Originally Posted by CTScott

Any momentary switch is fine. You are switching an analog input to a microcontroller, so the current is negligible.

For the resistors the tolerance means how far they can be off, so a 100 ohm, 5% can be 95 to 105 ohms. Since it is a plus or minus rating, chaining them together means that they can cancel each other out, or add to the percentage off in either direction. If you have a multimeter, you can measure the actual resistance of each.

thx for the quick reply. what then would be the permitted resistance ratings to get this to work? I plan on just using 2 switches, listed is 240 and 390-- how close should i be to that?

[scape]

actually looking back at the wiring for two buttons, one single resistor of 630ohm seems like it would work-- between the two buttons on positive; still not sure about the set-cc pushbutton resistances range though

[CTScott]

Originally Posted by scape

thx for the quick reply. what then would be the permitted resistance ratings to get this to work? I plan on just using 2 switches, listed is 240 and 390-- how close should i be to that?

You can use any value within these ranges:
216 to 264 ohms for one between resume and on/off
351 to 426 ohms for the one between set and resume
819 to 1001 ohms for the one between set and cancel

For the two button method, a single resistor 567 to 690 ohms can replace the 240 and 390 ohm resistors.

For current rating of the resistors, like the switches, it really doesn't matter, so 1/8 W, 1/4 W, 1/2 W, etc. are all fine.