quick question

Hopefully this is a quick question, i have a lock, it needs 5v to open, i am using a Arduino Diecimila and when i connect this lock to the 5V Power and Gnd connection on the board it opens and my meter shows the 5v connection.

But when i connect to say one of the digital outs and GND and have it digitalWrite( 3, HIGH) it does not open.

When i do not have it connected to the lock, the digital out shows that it is putting out 5v(read from a meter) but when i connect it to the lock it only reads out about have that 2.5v

any ideas?

Probably because the arduino can't output enough current, so the it's output voltage drops off. Use a transistor (or FET or whatever) to drive it, This should help : Arduino Playground - HomePage I know it's for a solenoid but it'll work for the lock.

Alec

Good afternoon,

Im having a similar problem but with small 3.5v bulbs. when using the 3v output fromt he arduino it lights but from digital pin it doesnt.

Been testing with some transistors but cant seem to get a result i expect.

I have 2 types of transistor a 2N2222A and a BD139 (i think this is a 12v power transistor)

Having looked at your circuit im sure i tried this but will give it a go with the 2.2 res.

Cheers.

PS im trying to light the bulbs from the power/hdd led output on a pc motherboard.

Having looked at your circuit im sure i tried this but will give it a go with the 2.2 res.

It makes little difference if you use a 1K or a 2K2, if it didn't work you didn't wire it up right.

using a meter im getting .2v across the diode, where am i going wrong?

Fixed it, my transistor wasnt up to the job, swapped the 2N2222A for the BD139 and we are in business.

Thanks guys

i figured it had to be something like that, thanks!