Re: Bowden's BCD clock circuit

Lord Garth wrote:
"John Popelish" <jpopelish@xxxxxxxx> wrote in message
news:xeadncEygpZ_AYDbnZ2dnUVZ_o3inZ2d@xxxxxxxxxxxxxxx
Lord Garth wrote:
"Greg" <ask@xxxxxxxxxxxxxxx> wrote in message
news:q54r139a01qg4vln9of4us0cgcfg8k4spc@xxxxxxxxxx
I've decided to build a BCD clock and after searching for a circuit
I've decided on Bill Bowden's circuit.

http://ourworld.compuserve.com/homepages/Bill_Bowden/clock.htm

After examining the circuit, though, I'm curious about the circuit
giving a pulse every second. There are two NAND gates attached to the
4040 binary counter which then feed into an OR gate. Am I correct in
assuming that they should be feeding into AND gate to get a pulse
every second? As the circuit stands, I would think it's going to give
a pulse on 0.8 sec and on 0.2 sec, or two pulses per second.

I'm fairly weak on logic circuits so forgive the stupid question.
View in fixed width font.

4040
+---\/---+
1 -|Q11 Vdd|- 16
2 -|Q5 Q10|- 15
3 -|Q4 Q9|- 14
4 -|Q6 Q7|- 13
5 -|Q3 Q8|- 12
6 -|Q2 R|- 11
7 -|Q1 /CP|- 10
8 -|Vss Q0|- 9
+--------+

Pin 6, 5, 3, 2 are 8+16+32+64 which equals 120 as the divisor
so you'll get 1 pulse per second due to the full wave rectifier at
the power supply.
What you call Q0 (and my data *** calls Q1) is the 1 bit
of the count. So pins 6,5,3,2 are the count bits
representing 4,8,16 and 32. The counter is fed with AC
upstream of the rectifier.

Now THAT I didn't notice. Does your data *** top out at Q12?

The one I posted a link to, has all Q values 1 higher than this lovely picture.

.

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