hex inverter delay circuit not working

[mstram]

I created a simple circuit with two ClockVoltage sources (digital oscillators). The first one goes directly to an LED, the second one is fed through 6 hex inverters to delay the circuit. There are 3 'tap' points after every two inverters connected to a (virtual) oscilliscope.

With 'real simulation' settings, the 'tapped' points show no delay on the oscilliscope. With 'ideal' settings chosen, the 'tapped' points display just a flat waveform.

Here are pics :

http://putfile.com/pic.php?pic=main/...5569.jpg&s=f10
http://putfile.com/pic.php?pic=main/...2134.jpg&s=f10

I also set up the same circuit in MicroCap, and it does show the delayed waveforms :

http://putfile.com/pic.php?pic=main/7/19516302012.jpg&s=f10

Mike

[Bhavesh]

Mike,

The issue with your attached circuit was that it was not wired together properly. If you look at your original circuit  that you posted and you select-and-move any of the hex-inverters you will notice that there is no net (wire) attached to it. That is why you are having an issue with your simulation. When placing just look for a red-dot to appear at the pins when attaching components together. This will indicate that the two pins are attached and not just over-lapping one another.

I have attached the file with the nets connected.

Please also note when you are using digital components and you are using "Real" simulation settings (in Multisim 9 you get to this by going to Simulate --> Digital Simulation Settings) you do need to place power components to properly simulate. Although there are no pins to actually connect the component (i.e. there are no power pins shown on the component symbol) if you place things like VCC or GND (digital ground) onto the schematic it will make a virtual connection to properly power the device. To check which power devices are necessary double-click on the digital component and select the Pins tab. You will see here which power components need to be placed on the schematic, for example VCC, GND etc....

I have done this in the attached file so you will see what this looks like.

[mstram]

Bhavesh,

DUHHHHHHHHHHHHHHHH !!!!!!!!!!!!!!!

THANK YOU !

Oh man, maybe eventually I might have gone and checked the connections but I ASSumed they were all connected !

Normally I explicitly *do* connect components by clicking on the device pin and dragging it to the next component's pin until I see the "dot".

With this circuit I thought I'd discoverd "automagic" wiring, as when one component is dragged close enough to another and their pins are in proximity to each other they automatically connect. I just tried it and it does work, but you have to SEE THE DOT. It looks like I ignored that critical detail ;), As I just ASSumed when the wires overlapped they were connected 😉

(virtual) wiring in MS9 can be aggravating sometimes as even with the mouse pointer right over a pin the program doesn't always "find" a connection. Zooming the view, moving the components further apart and moving wires around seems to help.

Thanks very much again for solving this dumb little problem that was bugging the heck out of me 🙂

Mike

** edit **

Actually it's a bit strange ("feature not a bug" ?) that the circuit simulates with an(multiple) *open* connection(s).

** I just found the 'electrical rules check' / 'report open pins' command. **

Message Edited by mstram on 07-17-2006 03:27 PM