How to make a 59-0 down counter?

Thread Starter

lildawg

Joined May 28, 2009
3
I found this schematic to make an up-down counter.. however all I need is a down counter starting from 59-0.. I've been staring at this circuit for hours but still havent figured out a way to simplify this circuit. Is there any way I can do it? thanks


http://members.shaw.ca/roma/up-down.gif
 

mik3

Joined Feb 4, 2008
4,846
Connect a 10K resistor between the emitter of the transistor and ground.
 

Thread Starter

lildawg

Joined May 28, 2009
3
what is the function of the resistor at the emitter of the transistor? as a pull down resistor?
 

mik3

Joined Feb 4, 2008
4,846
what is the function of the resistor at the emitter of the transistor? as a pull down resistor?
Yes, it pulls the input of the counter to 0V when the transistor is off. Without it the input will 'float'. A TTL chip would read a floating input as high but a MOS chip would have an unknown logic state.
 
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