Why is my 7 segment display not working in Multisim?

[lissette]

I was wiring my circuit in Multisim which has a 7 segment display (common anode). I connected common anode to +5 through a 330 resistor. Then I was connecting pins for a-g to the circuit I constructed. I know the circuit is correct because I simply put probes to see if the outputs were correct and they were, although when I connected the outputs of my circuit to the 7 segment display I keep getting an error. Does anybody have an idea why or what I should try?

 

[dlgoff]

...I keep getting an error. Does anybody have an idea why or what I should try?

What error are you referring to?

 

[julee]

May be it is a common cathode one.

 

[Herlene]

I'm having the same problem here, can anybody help? It is an common anode. I tried putting probe at the outputs of they decade counter and they light up all right. But the seven segment desplay just wouldn't light up!

 

[vk6kro]

The 7447 is a decoder which turns Binary Coded Decimal to 7 segment output.

If an output is low, it will sink current from a LED of the display. So, if you are seeing all high outputs, then the LEDs will be turned off.

The 7447 has a lamp test feature. You connect the "LT" pin (pin 3) to ground and all outputs (QA to QG) should go low and turn on all segments of the display.

 

[Herlene]

The 7447 is a decoder which turns Binary Coded Decimal to 7 segment output.

If an output is low, it will sink current from a LED of the display. So, if you are seeing all high outputs, then the LEDs will be turned off.

Th 7447 has a lamp test feature. You connect the "LT" pin (pin 3) to ground and all outputs (QA to QG) should go low and turn on all segments of the display.

Thanks for the tip...I grounded the LT pin but the outputs were still HIGH.

 

[vk6kro]

The diagram doesn't show power (5 volts) on pin 16 or ground on pin 8. Are these really connected?

 

[Herlene]

The diagram doesn't show power (5 volts) on pin 16 or ground on pin 8. Are these really connected?

yeah...here in multisim the pins are not shown and there is no need to connect them since they are already connected by default, I think. I've experimented with other IC and there is no problem.

 

[vk6kro]

I found a website that seems to deal with this.

http://forums.ni.com/ni/board/message?board.id=370&thread.id=2287

However, it does suggest putting 12 volts on TTL devices, which is crazy.
The other suggestions may be useful, though and even the 12 V one won't really blow anything up in a simulator.

I have an old EWB but not Multisim, so I can't try them.

 

[Jack Chappy]

I home school my 12 year old son. We do an electronic lab every week.

This is a working Binary into a 7-segment display EWB circuit.

I build this circuit for my son to simulate and to create a truth table.



Let me know how it works out for you:

Jack

 

[BenchTop]

wrong thread, sorry