non-multiplexed digital clock question

Thread Starter

cbuchakjian

Joined Feb 13, 2009
5
gentlemen and ladies,
I am attempting to build a digital clock with a four 7-segment characters. Each of my segments is a A/C device switched by an SSR. Is there a digital clock circuit which can drive four 7-segment characters without Multiplexing?
 

beenthere

Joined Apr 20, 2004
15,819
Of course - you simply use one 7 segment driver per display. Can a 7 segment driver IC actually turn on your SSR's, or do you need to buffer the logic output?
 

Thread Starter

cbuchakjian

Joined Feb 13, 2009
5
Thank you for your response. I should let you know that my knowledge of electronic circuits is somewhere between beginner and monkey. Multiple seven segment driver ICs makes sense to me. What IC combination would you recommend for the actual timing.

Hmm, what is the possibility that I could bump up the D/C output from the seven segment display so that the SSRs would still operate, say, 10 feet away?
 

beenthere

Joined Apr 20, 2004
15,819
4000 series CMOS is pretty available and functional. CD4029's are easy enough to use, a CD4511 or CD4513 will run the displays.

Lots easier to keep the relays close and just wire over to the displays. You do know that SSR's latch on with DC? Probably do ok with rectified but not filtered DC. CMOS can't handle power, so sone buffer might be needed between the logic output and the SSR's.

Any particular reason for using SSR's? There's less expensive ways to switch DC currents.
 

Thread Starter

cbuchakjian

Joined Feb 13, 2009
5
I chose the SSRs because they were the first thing that made sense to me for switching 2 amps of A/C with a small D/C current. If there is a more elegant (less expensive) solution I am all ears.
 

beenthere

Joined Apr 20, 2004
15,819
I'm confused. When you said -
bump up the D/C output from the seven segment display so that the SSRs would still operate
- imagined you were dealing with DC.

How are the 7 segment displays to be lit?
 

Thread Starter

cbuchakjian

Joined Feb 13, 2009
5
each segment of the 7-segment digit will we be a 3', T-12 fluorescent fixture. I just moved to a new workshop with a large wall perfectly suited for a 6' digital clock
 

Thread Starter

cbuchakjian

Joined Feb 13, 2009
5
I was able to get a ballast to fire by poking around on a clock that I built from a kit. The SSRs fire, but they don't react well to the mutiplexed signal. I believe that was your question.

Where would I find plans for a clock circuit with four 7-segment decoders?
 
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