I've used Teensy microcontrollers to program salvaged vacuum fluorescent displays many times, driving them with ULN2803 Darlington arrays and driving the filament either directly off the 3V or with 4 GPIO pins and an h-bridge. Teensys being scarce these days I thought I could make a vfd shield to place on a Grand Central Express M4 but as soon as I upload Arduino code connecting any pins to the transistor arrays the processor gets hot, a little hot to the touch with a couple grid and segment pins, and overheats quickly with all of them. The 20V to the segment and grid pins (with 47k resistors) is provided from a buck booster powered from the GC 5V, which is also how I do it with Teensys. Can anyone see why the GC would be overheating like this?
Thanks!
Driving vfd Grand Central chip gets hot
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- adafruit_support_mike
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Re: Driving vfd Grand Central chip gets hot
Post a photo showing your hardware and connections and we'll take a look. 800x600 images usually work best.
- enauman
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- Joined: Sat Dec 26, 2020 12:16 am
Re: Driving vfd Grand Central chip gets hot
Oh geez, I put the Darlington arrays in backwards...
- adafruit_support_mike
- Posts: 67485
- Joined: Thu Feb 11, 2010 2:51 pm
Re: Driving vfd Grand Central chip gets hot
Ah.. that will do it.
You're probably sending current through the input protection diodes on the ULN2803 pins. Hopefully that won't translate to any long-term damage to the Grand Central.
You're probably sending current through the input protection diodes on the ULN2803 pins. Hopefully that won't translate to any long-term damage to the Grand Central.
Please be positive and constructive with your questions and comments.