Weird Problem

Here's the Oomlout tutorial, which provides a pretty clear schematic too. Assuming you're using a different tutorial, this might help by giving another angle on it.

http://www.oomlout.com/oom.php/products/ardx/circ-03

Cheers,

-Nico

quite funny really, I was using the 2N2222A2N2222A yesterday to drive 12v relays with a 5v signal from a TTL And gate

I used a 4k7 to feed the base and the base also had a 20k pull-down resistor (so nothing bad happens if I pull the AND chip).

I`m thinking that IF the transistor is ok, could the Back EMF protection diode be forward biased?

4k7 ?

YT2095 u have a schem of that project ?

Message was edited by: Pablo Garcia

4k7 ?

YT2095 u have a schem of that project ?

Message was edited by: Pablo Garcia

No, I haven`t drawn one yet, but I can do if you like, I`ll probably post it in my Blog when I do a write-up for my latest Robot build, it`s very rare that I actually write any of my circuits down to be honest.

also 4k7 is just the same as 4.7k (4700 ohms), I just write it that way out of habit

it kinda through me off a bit like wtf lol but yea a 4.7k idk i havnt seen any schem other then 1k so if ur having a similer problem try using a 1k seen lot of schem's with 1k if u have the time make a schem in cad soft eagle helps when ur not to sure it allows u to see where u wired it in i fried a L298HN it helps when u build it or draw it making ur own datasheet

my circuit works perfectly with the 4k7, I`v just drawn it out for you here:

it`s not perfect and may need magnifying a little? but it works great (I have a board with 8 of these on that have been working well for nearly a decade), so this same CCT will also be suitable for the Original post, just swap out the Relay coil for your motor, and the AND gate should be the arduino pin.

I`m using 12v on mine as that`s what the relays needed, but 5V will work too

hermm try it with out the 20k or u tried it ?

if not then play with a 1k as well the 1k  and put that 20k just playing with safe resistors till it get it

Message was edited by: Pablo Garcia

the circuit above is already built and working in my Robot, I need the 20k pull-down in case I ever have to pull the 74LS0874LS08 chip with power on.

it`s not a small robot, and so I need plenty of fail-safes to prevent it going crazy in the house and wrecking stuff, my 3 year old son can ride on it!

so for every stage, the Default state has to be OFF.

here`s a sneak preview of the board:

like i seid im still new to arduino here what it say on the volt meter ? on the other 1 u made i have a buggie transistor it was a 2N2222A2N2222A it was noticeable in the volt meter guess was a bad batch of transistors it works but the current was fluxuating very bad that so far i know with 2N2222A2N2222A

Im leaning as i go i use to repair well get part for my brother to repair car radios and amps they even got me a experament back in 1986 i had memorized all componets part in a radio and amps but it been a whil sense i repaired a radio im trying to rememoriz all resistor transistors resistor and so on and leaning arduinos at the same time

that a interesting setup alot diff from my friend setup he toke a kids razor Gokart controller and hocked up a arduino robot the robot has a hitch to hock up a trailer the robot pull and parks the trailer boat becus his brother has 1 arm he built it for him to help him park the trailer

whoa pc been dead for a while im back have u figured out the problem ?