Won't light up!

bubby9534 · 2012-01-30 09:28

I have a BS2 BOEBOARD and have this panel of lights

and I plug the first light into vss and vdd and it lights up.

I plug more lights in and they light up

but when I plug in the first light to vss and pin 15 with pin 15 blinking HIGH, pause .5 seconds, LOW, pause half a second nothing happens.

I believe it is because of a power loss, but I don't know! I am new to electrical engineering

Mike Green · 2012-01-30 09:35

Those are incandescent lamps. They probably draw 100mA or more each. A Stamp I/O pin is capable of handling 20mA, maybe 25mA. Typical LEDs will draw at most around 20mA, so that's why you can use LEDs directly, but not your incandescent lamps. Look at Nuts and Volts Column #6 for a discussion of how to control high current devices with a Stamp using a switching transistor. Go to the main Parallax webpage and click on the Resources tab and you'll see a link to the Nuts and Volts Columns index. The examples in that Column control relays and motors and show a reverse connected diode across the load. You don't need the diode for incandescent lamps.

Don't be surprised if your 9V battery runs down quickly. Those lamps draw a lot of power and those little batteries don't have much capacity. You'd be much better off with an AC adapter that supplies 6V to 7.5V at currents up to 1A or a battery pack using AA or larger batteries containing 4 or 5 cells. You can get battery holders at RadioShack. I'd use size C or D and use a 4-cell holder in series with a single cell holder. If you change to NiMH rechargables, you won't want to use only 4 cells ... the overall voltage is too low. With 5 cells, you can use either alkaline or rechargable NiMH cells.

bubby9534 · 2012-01-30 09:37

Thanks for the response within 60 seconds

, will try. Thanks!

bubby9534 · 2012-01-30 09:42

Did a switching transistor come with the BOE BOARD starter kit?

Mike Green · 2012-01-30 10:48

You can get little packages of switching transistors at RadioShack. Look for MPS2222A (2N2222A) or 2N3904 or 2N4401. Any of those should work.

bsnut · 2012-01-31 01:11

Mike Green wrote: »

You can get little packages of switching transistors at RadioShack. Look for MPS2222A (2N2222A) or 2N3904 or 2N4401. Any of those should work.

If they don't have any of them, then you can use a ULN2003 or a ULN2803 and they can handle up to 5000mA.

erco · 2012-01-31 08:59

bsnut wrote: »

If they don't have any of them, then you can use a ULN2003 or a ULN2803 and they can handle up to 5000mA.

Ahem, that's 500 ma!

Won't light up!

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