[Moved] interfacing a ULN2003an to the output of a CD4017BE counter

[cayote11]

Hi. I am trying to build a 3 phase driver circuit using a XR2209 osc chip as the clock source, feeding a CD4017B counter looped at the third output to provide a 'johnson' ring counter. The first two stages of the circuit work fine, but when I tried to connect the ULN2003an darlington array to the counter, I only get very low pulses on the output, maybe 200mv levels coming out maximum. I tried 1K ohm
pullup resistors to the open collector outputs of the ULN2003, but no help? I am driving a 6 coil load. The coils are connected to 12vdc, the pulses are about 10vp/p coming from the counter, and the oscillator pulses are 12vp/p. Thanks in advance for any design suggestions.
cayote11

 

[FvM]

Simple explanation, a 1k pull-up resistor can't drive your coil. You need some kind of push-pull phase drivers.

 

[cayote11]

suggesting another chip for push pull output from the cd4017 counter

Hi
Thanks for the feedback. I am suggesting the use of a L296D 4 stage push pull driver instead of the ULN2003. Seems like it would work on my board with little or no support of extra discrete components? it too is 16 pin, will need to adjust circuitry to accommodate.