ELECTRONIC WATER LEVEL INDICATOR & CONTROLLER With LM3914

hhhunzai

Joined Nov 14, 2011
72
As I said in my #17th post,. I was using a low amperage regulator, 78L12, it was only 100mA of amperage, my transformer was 800mA.
Now I am converting it to 7812, so do u think this should be the problem of circuit?

KMoffett

Joined Dec 19, 2007
2,918
Did you measure a drop in output voltage as the circuit operated with the 78L12?

Ken

hhhunzai

Joined Nov 14, 2011
72
Yes there were 11.97volts DC, now the problem is same with new supply, I have just tested it with new supply whose output is 12.06VDC, that I have made.
So tomorrow, I will connect an extra IC in a bread board and do some experiments on it and will tell u about the results.

Please clarify me a confusion, that is how this NAND gate gives output, when both the inputs are high, the truth table of NAND gate says it should not give the output when its both inputs are high?

http://en.wikipedia.org/wiki/NAND_logic

Please refer AND for NAND results, inversion of AND is NAND.
Am I right?

KMoffett

Joined Dec 19, 2007
2,918
The difference between 11.97V, 12.00V, and 12.06V is insignificant. I don't think your power supply is the problem.
The 4093 is a NAND gate with an output that is "driven" either high (source) or low (sink).
If both inputs are low (~0V), or one input is low( ~0V) and one is high (~Vdd), the output is high and will supply voltage (~Vdd) to a load.
If both inputs are high (~Vdd) the output will pull a load to ground (~0v). That's how the detector gates' outputs drive the LEDs.

Ken

hhhunzai

Joined Nov 14, 2011
72
During testing I damaged an extra IC 4093, in addition of the others ones, I don,t know why. I made a circuit on a breadboard.
I connected C13 0.0068μF instead of 0.001μF grater than the given in schematic due to non availability.
Please advice me on this, is this was the reason of burning of IC 4093...?

hhhunzai

Joined Nov 14, 2011
72
Hello Mr. Ken,
How r u? Hope u will be fine there.
I want to take a suggestion from you, please tell me about it.
I want to check this circuit in Multisim software, If this is possible to check this circuit on an evaluation version please guide about this.
and if it is possible guide me a little about it.

KMoffett

Joined Dec 19, 2007
2,918
I'm fine, thank you.
Sorry, I can't help you emulate the circuit in Multisim or any other electronics simulator program. I don't use them.

Ken

hhhunzai

Joined Nov 14, 2011
72
Ok doesn't matter, I will try it myself.
Have you tested this circuit or not?
Please let me know if I will change these CMOS ICs with TTL ICs is it possible for this circuit or not?
If I will change it what will happen to the circuit.
Because I am thinking the ICs are damaging due to some statics electricity.

KMoffett

Joined Dec 19, 2007
2,918
No, I have not tried the whole circuit, only the oscillator/detector portions. The circuit will not work with TTL. The detectors need high impedance input gates. On this type of prototype circuit I usually use IC sockets on the perfboard, just in case I blow one.

Ken

hhhunzai

Joined Nov 14, 2011
72
Yes you are right I will do it in my next project, I will use sockets for all ICs.
This was my first time of fabricating a full circuit, with ICs.
Now Mr. Ken what do u suggest me, should I replace all three ICs with new ones?

KMoffett

Joined Dec 19, 2007
2,918
I would remove IC1 first. Plug it into a breadboard and connect the pins 14 and 7 the the +12v and ground busses. Connect both inputs on each gate to a 10K pullup resistor and connect the four pullup resistors to ground buss. Connect the 12V supply to the +12v and ground busses. verify that aAll outputs should be high with your DVM. One at a time, connect the gates' inputs to +12v and see if the outputs go low. If they do, than you have a good IC and you likely have a wiring error on the perf board.

Ken

hhhunzai

Joined Nov 14, 2011
72
Do you have any kind of software for making such schematic?

KMoffett

Joined Dec 19, 2007
2,918
I designed the circuit using my experience, and bits and pieces of circuits from various sources. The schematic was created with a free PCB development program from ExpressPCB. http://www.expresspcb.com/

Ken

hhhunzai

Joined Nov 14, 2011
72
No doubt sir, I am benefiting from your knowledge and experiences as well as learning the basic of designing circuits in your guidance.
My intentions of asking about software were, I am trying to make this circuit in Multisim 11 and fabricate on breadboard in Multisim.
I am facing a problem regarding the power supply in it therefore I asked about the software.
The symbols you have used are so good but in multisim it is difficult to connect power source to the pin # 14 and #7 for energizing the IC.

hhhunzai

Joined Nov 14, 2011
72
Mr. Komffet,
Please don't quit this project ok, I am working on this circuit, but due to shortage of time I am unable to get the new ICs as I have to purchase them from a different city which is enough far away from me.
when I will get those ICs agin we will start discussion.
Thank you.

KMoffett

Joined Dec 19, 2007
2,918
I'm still here

Ken

hhhunzai

Joined Nov 14, 2011
72
I can't post a new thread please guide me in this regards

KMoffett

Joined Dec 19, 2007
2,918
I don't understand. You can't make a new post to this thread? Or, you can't create a new thread?

Ken