SparkFun will be closed Nov 26th and 27th for the Thanksgiving holiday. Orders placed after 2:00pm MT on the 25th will ship out Monday the 30th.


Member Since: October 6, 2011

Country: United States



Assistant Professor at UFRN



Spoken Languages

Portuguese, English, French



  • Hi all, I’m using the ED with a 556 to generate two pulse trains (ck1 and ck2), instead of a microcontroller. Ck1 is variable through a potentiometer and is connected to STEP to vary speed. Ck2 has a much less frequency (around 0.1 Hz) and is used to alternate direction. The DIR input is pulled-up to 5V through a10K resistor and connected to ck2 through a switch, so I can choose (from the switch) to operate in only one direction or alternating directions (this project is simply to control the speed and direction of a stirrer so I don’t need a uC). The problem is that the DIR input, initially high impedance, after some time seems to get shortened and drives a high current from the 556 output, which gets hot. Also the “shortening” invalidates the purpose of the 10k resistor, since it does not drive enough current to sustain the desired direction (the 556 and ED are still working, though I don’t know until when). I bought two ED and this issue has happened with both of them. Has someone experienced any problems with high current in the DIR input? I’d appreciate any help on this.

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