On 1/9/12 8:51 AM, David Forbes wrote:
On 1/9/12 7:03 AM, Imbanon wrote:
Hi everyone.
First of all, I wish you a happy New Year and all the best!
Even after searching the whole group, I have some questions about
multiplexing, now that I've finally received my spare uC.
I am using this schematic http://www. imageshack .us/photo/my-images/
209/anodecontrol .png (remove spaces) to control lighting of each
IN-14 nixie in my 6x muxing. You might have noticed the R4 having the
value of 0.00 ohm. As I noticed the lack of current through the
You need to use a PNP transistor, MPSA92, for the anode switch.
An NPN will never turn on the Nixie tube, because the base has to be
more positive than the emitter, and that's not possible in the circuit
you published.
Sorry, I'm wrong above. I get so used to doing it one way that I forget
that there is a second way to turn Nixies on and off.
You need to find out where the problem lies.
As a test, disconnect R2 from the circuit and see if the Nixie lights up.
If so, then the problem is in the left side of the circuit. If not, the
problem is on the right side of the circuit.
If the left side is bad, then try increasing R1 to about 22K, and if
that is not sufficient, then add a 4.7K from the emitter to the base of
that transistor.
If the right side is bad, then try a somewhat lower resistor value for
R3. Not too low, though.
On an unrelated note, the advantage of using a PNP anode transistor is
that it doesn't waste power in all the R2-R3 stacks for unlit digits.
--
David Forbes, Tucson AZ
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