good at smoking chips

[brittio]

I've smoked several uln's now and this last one may have taken the cake...  I've got some second hand solenoids that are giving me fits and in the process of fighting them I touched some wires that I shouldn't have.  The ULN smoked and I replaced it, reloaded the program and now the prop-1 won't do anything when triggered.  If I change the jumper to UP it will continually go through the program, but the only thing that actually runs is the AP-8 that I have connected via serial cable.  When I connect my prop-1 trainer none of the LEDs light.

[JonnyMac]

Regrettably, you may have killed your controller.  The ULN does have a specification that is listed in our documentation -- if you exceed that specification you can damage the ULN and, in extreme cases, even damage the Prop-1 controller.  Normally when the ULN fails it fails "open" (like a fuse) and the damage stops at that chip.  If, however, you have a really heinous overload then the chip can melt internally (creating a giant short); what you end up with is a connection between V+ (12 or 24 volts) and the I/O pins of the processor which can only tolerate 5 volts. 

I'm guessing that the reason the AP-8 sill works is that you had a ULN2003A installed or clipped pin 1 of the ULN2803A, so the V+ voltage never made it to P7.

Before there are any more problems.... what is the specification of the solenoid that you're attempting to control?  It should have a wattage rating.  From there and knowing your V+ voltage we can determine the current needed for the device and then check it against the ULN.  There are some solenoids that the ULN can't take and you may need to put a small relay between the ULN and the solenoid (or find a different solenoid).

And please (this is for everyone): If you connect an unknown device to one of our products and create smoke, don't reconnect that device without calling us (916-616-1658)  and chatting about it.  The only thing we like less than these things happening is these things happening more than once to the same friend.

[gadget-evilusions]

I smoked a uln this weekend also, i am embarassed to say i reversed the voltage to my prop-1, actually, the uln not only smoked but shot a chunk of itself at my eye. Needless to say i wont be accidentaly doing that again.

[JonnyMac]

Did the Prop-1 survive the reverse voltage?  They're pretty tough, but can't take a lot of reverse current.

[livinlowe]

Well, thats one way to have a Happy 4th!  ;)

[brittio]

Mine shot a chunk too...  I think a loose wire from one of my pins hit the 120v I had connected to a relay.

The solenoids are 24VDC and 5.4 watts.

[JonnyMac]

Your solenoids should be fine; they'll draw about 225 mA (see this post for a related discussion: http://www.efx-tek.com/php/smf/index.php?topic=160.0).  If you keep within the ULN specs you can run five at a time.  You may not want to start all five at once, however, as the accumulated inrush current will probably exceed the ULN specifications.

If you had contact with 120 VAC you have most certainly killed the controller....

[gadget-evilusions]

Controller survived reverse voltage for about 10 seconds until i pulled the plug. Put in a new uln and all was good to go! You guys build these things like tanks. That's good when I am involved.