Please anybody troubleshoot my circuit

[mindwork]

Hi!

I have constructed the automatic room light project available on the following webadderss

www.electronic-circuits-diagrams.com/ lightsimages/lightsckt4.shtml

it is an automatic room light circuit,everything is ok,switching is also perfect, but the counting in the circuit is malaceous

i.e the circuit is not counting properly as mentioned at the website

it supports entrance of 4 persons but in my circuit the switching is in a malaceous order .
Note:i have triple checked my work and did not find any problem in any part of my handwork ,
please guide me is there any technical error in the circuit or .is it the problem with my counter ic CD4017 or is the circuit having some error

please guide me because i am submitting this project for my finla semester and i am running out of time.

hoping for a quick and prompt reply from you all.
thanking you ,yours faithfully

 

[dingo]

without looking to close at the logic, one thing I see straight off is the outputs on the decade counters. Looks like they might be one out. try changing the following pins.

2 - 3
4 - 2
7 - 4
10 - 7
1 - 10

They have used output 1 as the first counted (pin 2) but output 0 (pin 3) is the first clocked after reset.

 

[Russlk]

Your problem is that pin 14 of IC3 and IC4 is floating. It must have a DC return to either VCC or GND.

 

[dingo]

Talk about a screwy circuit.

As far as I can tell all those transistors, caps and stuff in the middle of the circuit are to inhibit whatever beam is crossed second so you can tell if the person is coming or going, it just seems like a hard way to go about it.

If you want to rid yourself of 20 odd components you could do the following.
Pin3 IC1 connect to Pin 14 IC 3 and Pin 4 IC 2. Disconnect all else.
Pin3 IC2 connect to Pin 14 IC 4 and Pin 4 IC 1. Disconnect all else.
This will cause beam 1 555ic to hold beam 2 555ic in reset if it is tripped first and visa versa. You need to make sure the 555 timer is set for long enough to allow you to pass both beams.


Also don't forget to do what i said in the above post or your first pass on both going in and out will not count.

 

[dingo]

Eeeek!!

Got to stop looking at this circuit

Both on IC's 3 & 4 pins 1 & 15 are tied, the idea being that the 5th person that enters (in this case the 6th as they forgot about output 0) resets the counter. Now this is all well and good except if you push that reset button you will short out the gate at pin 1 so you have most likely blown both chips. Connect a resistor on pin 1 (or pin 10 when you fix the counting order) so it will not short the gate when you push the button, 1k or over should be ok.

 

[dingo]

The more I look at that circuirt.....7 amp diodes, 5v and 9v power rails ...mmmmmmmm


Have drawn up a quick circuit if you want to have a go at that instead. I used the input part with the LDRs and 555s exactly as the were in the original drawing so if that bit doesn't work........just modified the outputs to reset the other 555.

This circuit uses a 4bit up down counter so can count up tp 15 people.

Untested 15 person counter
**broken link removed**

 

[mechie]

Throw a wobbler?

I am glad Dingo and Russlk have come to these conclusions -
this self - same circuit was discussed ages ago (can't find it at the mo.)
and we came to similar conclusions - circuit far too complex for its job and poorly thought through.
We never went as far as redesigning it though !

Honestly, the stuff you can get from "certain other :roll: " websites if your'e not careful/lucky!