7 segment driver help

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
Post Reply
PainGypsy
Posts: 12
Joined: Thu Mar 27, 2003 1:01 am
Contact:

7 segment driver help

Post by PainGypsy » Thu May 08, 2003 5:23 am

I am New to electronics and just trying some things out. I am working on getting a 7 segment display to work. I have a 555 a 4024 and a 9368 as well as a radio shack 7 segment common cathode display. I have everything hooked up like I believe it should be. all of the 4024's q's to the 9368's a's and what not. what I am getting is this. I have pulses and it seems to count, but the display Never lights up at all. I checked the voltage at the display and it seems that I am not getting positive voltage from the 9368. I think I must be confused about something simple. Cathode of display is conected to the ground and when I put positive voltage the the segment connector manualy the led lights up. I would think that when the segment is to be lit, + would come from the 9368 but... :\ what am I doing wrong?<p>oh yeah I also have the 555 pulse going to the LE on the 9368. and I have a 556 available if I need it.

L. Daniel Rosa
Posts: 400
Joined: Tue Dec 25, 2001 1:01 am
Location: Bellingham, WA
Contact:

Re: 7 segment driver help

Post by L. Daniel Rosa » Thu May 08, 2003 11:52 am

With the 9368, if pin 5 is low and the inputs are all low the outputs will be blanked. Also if pin 4 is low, the outputs will be blanked regardless of the inputs. If pin 3 is high, then changes in the inputs will be ignored and the outputs will not change. For the data sheet look in http://www.fairchildsemi.com/pf/DM/DM9368.html .<p>If you want the data sheet on the 4024 as well it is available at http://www.fairchildsemi.com/pf/CD/CD4024BC.html .

russlk
Posts: 563
Joined: Thu Dec 06, 2001 1:01 am
Location: New Hampshire
Contact:

Re: 7 segment driver help

Post by russlk » Thu May 08, 2003 11:56 am

I don't see any problem with your description, it should work unless there is some mis-wiring or the 9368 IC is dead.

PainGypsy
Posts: 12
Joined: Thu Mar 27, 2003 1:01 am
Contact:

Re: 7 segment driver help

Post by PainGypsy » Thu May 08, 2003 12:48 pm

Those are the exact two data sheets I have been using to hook it all up. what if I have nothingon pin 3 or 4, that is how I started, then I hooked the 555 pulse to it... The way I read it, it would basically check the 4024 state on the fall of each clock...? How do I force it to show the state?? and am I right in thinking it should be giving positive voltage out to the display ?<p>Thanks for the help btw :)

PainGypsy
Posts: 12
Joined: Thu Mar 27, 2003 1:01 am
Contact:

Re: 7 segment driver help

Post by PainGypsy » Thu May 08, 2003 4:13 pm

ok, one thing I understand pretty well is binary... I have a stong tcp/ip background. After hooking up some led's to the outs on the counter it seems to be counting DOWN... I don't think it should be doing that. It is definately counting down... if that helps figure this out at all. I also grounded pin 2 of the counter... Any and All help appreciated... Also, the voltage out of the counter is -4.92v and it seems to be 4mA as well... not too sure about metering amps yet... Sorry if I am not giving good data. I can post some pics if it would help.. but I don't think that if I had something so stupid as a ground and a + switched on a chip that it would even get this far... Help :\ !

russlk
Posts: 563
Joined: Thu Dec 06, 2001 1:01 am
Location: New Hampshire
Contact:

Re: 7 segment driver help

Post by russlk » Thu May 08, 2003 7:40 pm

The 4024 clocks on the falling edge of the pulse. Q1 will be 1/2 the clock freq, Q2 will be 1/4, etc. It is not possible for the 4024 to count down.

L. Daniel Rosa
Posts: 400
Joined: Tue Dec 25, 2001 1:01 am
Location: Bellingham, WA
Contact:

Re: 7 segment driver help

Post by L. Daniel Rosa » Fri May 09, 2003 10:10 am

"what if I have nothingon pin 3 or 4, that is how I started"<p>Having nothing on an input pin allows it to figure the best way to frustrate you. Unless it is critical the display not show the counting glitches, I'd suggest setting pin 3 low and pins 4 and 5 high. This should allow the display to show the value.

Post Reply

Who is online

Users browsing this forum: No registered users and 13 guests