<div dir="ltr">Hey Charles,<div><br></div><div>it seems like this might work. i got some pnp transistors and built the circuit from julianvogels site.</div><div>The only problem is that the LED on the test circuit barely lit up. I think it's because the transistors are not for 20mA, none were available. i'll check another electronics store to see if i find some.</div>
<div><br></div><div><img src="cid:ii_1405721c3fd77f93" alt="Inline image 1" width="363" height="420"><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Aug 5, 2013 at 6:42 AM, Charles Goyard <span dir="ltr"><<a href="mailto:cg@fsck.fr" target="_blank">cg@fsck.fr</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi,<br>
<br>
You're not doomed !<br>
<br>
There are two ways to solve your problem:<br>
<br>
The proper one is to use PNP transistors or P-channel mosfets (remember<br>
I already told you about that ? :))<br>
<br>
See this document, you can find the wiring at the end:<br>
<a href="http://julianvogels.de/wp-content/uploads/2013/06/stromkreis_transistorschaltung_final-1024x627.png" target="_blank">http://julianvogels.de/wp-content/uploads/2013/06/stromkreis_transistorschaltung_final-1024x627.png</a><br>
<br>
<a href="http://julianvogels.de/extending-pwm-output-pins-with-a-texas-instruments-tlc5940-led-driver/" target="_blank">http://julianvogels.de/extending-pwm-output-pins-with-a-texas-instruments-tlc5940-led-driver/</a><br>
<br>
<br>
The good enough one is to put a pull-up resistor (10k works) on every<br>
NPN transistor base, and use the TLC as a pull down. In this case, the<br>
on-time on the TLC corresponds to the off-time on the solenoid. Also<br>
when the arduino reboots and every time the BLANK is issued, every<br>
solenoid will act for a veeeeery short time. This can be a big problem<br>
in your project. I did this for a 96 channels motor+led strip system,<br>
and I regret not using PNPs instead.<br>
<br>
<br>
Enjoy,<br>
<br>
--<br>
Charles<br>
<div class="im"><br>
<br>
<br>
Epic Jefferson wrote:<br>
> Hey guys,<br>
><br>
> updating on this project. I got the pwm shields and i've hit a wall. The<br>
> driver circuit I'm using to control the solenoids via arduino is this one<br>
> from instructables<br>
</div>> (link<<a href="http://www.instructables.com/id/Controlling-solenoids-with-arduino/" target="_blank">http://www.instructables.com/id/Controlling-solenoids-with-arduino/</a>)>)<br>
<div class="im">> and<br>
> it uses a single pin to control the pwm signal.<br>
><br>
</div>> The pwm shield (link<<a href="http://www.practicalmaker.com/products/arduino-shields/pwm-shield-assembled" target="_blank">http://www.practicalmaker.com/products/arduino-shields/pwm-shield-assembled</a>>)<br>
<div class="im HOEnZb">> is<br>
> based on the tlc5940 which requires each pin to have it's own ground<br>
> instead of a common ground across all drivers. This is a problem because<br>
> all of the information i've found suggest that the signal from the pin<br>
> controls the gate (transistor - TIP102). But i think, in the case of the<br>
> tlc5940, the 5v supply is constant and the ground is being controlled,<br>
> that's why it works perfectly for LED's but seems to be ill suited for this<br>
> circuit.<br>
><br>
> Any suggestions on how to modify the instructables circuit for use with the<br>
> shields? or would the circuit have to completely change?<br>
<br>
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</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><a href="http://www.epicjefferson.com" target="_blank">www.epicjefferson.com</a><br><a href="http://www.avmachinists.org" target="_blank">www.avmachinists.org</a> Puerto Rico based Art Collective/ Non-Profit Org
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