I need help to start a project, which my grandson (11 years) and I (an old duffer of 75 ) intend for a summer holiday project. We want to create using 7 segment displays a "hymn board" in our local church. It needs to comprise at least 6 banks of three per bank of large 4" high seven-segment displays

A switch per bank will illuminate all "zeros" and then by using a push button switch per numeral, one is able to increment the number from 0 to 9. A simple incremental circuit. Thus Hymn no: 349 on bank 1, no 596 on bank 2 can be displayed. We could build a "bread-board" to experiment and having ironed out any snags, then build a prototype for the vicar's approval

I have some knowledge of electonics, having worked as a pcb draughtsman way back in the 1960's
I hope I have been explicit enough
Thank you very much
godwin penhyn-lowe

 

I need help to start a project,
godwin penhyn-lowe

Okay, to get us started, I would recommend you plan on using chips in the 4000 cmos series of counters and display drivers. This will enable you to choose from a range of operating voltages.

You will need one counter and one display driver per 7-segment display, in other words, 18 sets. The switch arrangement would be pretty straight-forward, but keep in mind that the switching will need to be debounced, in order to prevent accidental counts.

All of this can be researched in depth on the web by simply "googling" the various phrases.

I'm sure some others will chime in (no pun intended) with some additional advice.

Good Luck,
Eddy

 

The 4026 will is an up counter and display driver all in one. If driving multiple LED's per segment, then you would probably need to Buffer the outputs.
They will however drive a standard 7 seg display unbuffered.

 

If you display the same hymn number on all displays, the project may be realised with a three section thumbwheel switch, and 18 MC14511 seven segment latch/decoder/drivers. These 4511 would work most easily with common cathode displays. An aditional MC14011 quad NAND gate for debouncing the pushbutton latch switch and another switch to allow blanking the display (optional) would complete the materials.

Operation would be to set the desired number in the thumbwheel switches, and depress the latch pushbutton. This will latch the number into the decoder/drivers, and display the number on the displays.

All the circuit elements could be mounted in a central location. The wiring out to each display would be an eight wire cable (the seven segment lines plus the common ground).

If this is interesting, I can try to provide you with a schematic in a few days (life is busy).

 

Gadget's right. We may need some additional buffering to use big 4 inch displays. What are their current needs?

 

Thanks Eddie,Gadget and Beenthere I am obliged to you all. I am away next week, but will catch up on my return
Regards
Godwin