Best way to control multiple 1.5v lights including brightness

johnbot

I've got multiple 1.5 volt hobby type grain lights for which i need to control on/off status and individual brightness. Currently, I have them hooked up to a uln2803 but that doesn't allow me to change the light intensity. Is there some type of chip that i could shift intensity values into or something like that to control all these lamps individually? (7 lamps) What are my options?

PJAllen

johnbot said...
Is there some type of chip that i could shift intensity values into or something like that to control all these lamps individually?

http://www.parallax.com/detail.asp?product_id=28020

The PWMPAL has 4 programmable outputs.· I'm not certain whether you could use two with one Stamp.· Read over the documentation (via the link above.)

Phil Pilgrim (PhiPi)

Here's an option that's not as efficient as switching, but might work for your small lamps: TDA8444. It's an I2C-controlled, octal, 6-bit D/A converter. I've used it to control banks of IR LEDs, and it worked out fine. However, the voltage outputs can only source or sink 2mA, so each one will have to feed a current driver for its associated lamp. I used an array of LM317Ls for this purpose, but NPN transistors connected as emitter followers, or (even better) a couple quad op amps feeding transistor current drivers would serve the same purpose. In either event, make sure the associated resistors have a high enough wattage rating, and add heatsinking as needed.

-Phil