Hi, You're not doomed !
There are two ways to solve your problem: The proper one is to use PNP transistors or P-channel mosfets (remember I already told you about that ? :)) See this document, you can find the wiring at the end: http://julianvogels.de/wp-content/uploads/2013/06/stromkreis_transistorschaltung_final-1024x627.png http://julianvogels.de/extending-pwm-output-pins-with-a-texas-instruments-tlc5940-led-driver/ The good enough one is to put a pull-up resistor (10k works) on every NPN transistor base, and use the TLC as a pull down. In this case, the on-time on the TLC corresponds to the off-time on the solenoid. Also when the arduino reboots and every time the BLANK is issued, every solenoid will act for a veeeeery short time. This can be a big problem in your project. I did this for a 96 channels motor+led strip system, and I regret not using PNPs instead. Enjoy, -- Charles Epic Jefferson wrote: > Hey guys, > > updating on this project. I got the pwm shields and i've hit a wall. The > driver circuit I'm using to control the solenoids via arduino is this one > from instructables > (link<http://www.instructables.com/id/Controlling-solenoids-with-arduino/)>) > and > it uses a single pin to control the pwm signal. > > The pwm shield > (link<http://www.practicalmaker.com/products/arduino-shields/pwm-shield-assembled>) > is > based on the tlc5940 which requires each pin to have it's own ground > instead of a common ground across all drivers. This is a problem because > all of the information i've found suggest that the signal from the pin > controls the gate (transistor - TIP102). But i think, in the case of the > tlc5940, the 5v supply is constant and the ground is being controlled, > that's why it works perfectly for LED's but seems to be ill suited for this > circuit. > > Any suggestions on how to modify the instructables circuit for use with the > shields? or would the circuit have to completely change? _______________________________________________ [email protected] mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
