What's wrong with the circuit?

[Tipu606]

remove diode D4 1N4148 and then see, i do not find any function of diode D4 at pin 11 of the IC
also circuit diagram does not show pin 14 power supply connection for the IC

 

[Sunny55]

I think it might be wire size problem. I use the circuit with low current solar panel circuit works but not on car battery . Should i use thicker wire for this circuit?

 

[godfreyl]

Should i use thicker wire for this circuit?

No, you should figure out why the transistor isn't switching on properly. Wire diameter doesn't make any difference when the circuit isn't working.

 

[FvM]

Presumed everything is connected according to the schematic, you might have mixed up transistor collector and emitter pins.

 

[Sunny55]

Presumed everything is connected according to the schematic, you might have mixed up transistor collector and emitter pins.

Maybe the transistor or relay is damaged by high current? I was using some thin jumper wires today and it heats up.

 

[tpetar]

What relay did you use, what is (was) coil resistance ?

 

[godfreyl]

Make sure the transistor is saturated

It's not. He measured Vce = 7.45V when it's "on". Either the transistor is faulty or it's connected the wrong way around.

That much was established 3 days ago. For some reason Sunny prefers experimenting with different diameter wires etc rather than doing anything about the actual problem. :-?

 

[Felisberio]

Sunny test basic things.

- connect to 12 VDC power supply with sufficient current to drive the circuit and relay coil, (Cmos consume 50mA, Relay about 50mA). Probably you don´t have this current from the solar panel.
- Supply for relay and the circuit are different, relay should have 12VDC or more, cmos if supply accordingly to temperature of termistor;

- Using termistor and 12VDC power supply play attention to pot. R7=0 ohm as at 25º you have 2,1VDC to supply of cmos 4011 (Not working zone); with pot R7=10k ohm you should have close to 8,4V (Working zone). Check the supply to cmos if is correct (HEF4011B work from 3 to 15V). You say that "1" is around 7,45V for 13VDC at T=?.

- If this is ok, check the charge /discharge of condenser C1.
Initialy C1 charge by R1+R2 an D2 (Pin 4-2 = "1" logic; Pin 3-12-13 = "0" logic; Pin 11 = "1" logic and Transistor ON).
After Pin 5-6 reach the level of "1" (it should be betwenn 3,5 and 7V) and this varies with the supply to the cmos, output Pin 4-2 goes "0", Nand 1 switch to "1", Pin 3-12-13 = "1" logic; Pin 11 = "0" and transistor OFF;
C1 now discharge by R4+R3 and D1, and should repeat the cycle when Pin 5-6 reach the level of "0" (< 3,5V).

I think that is better to remove (shunt) termistor and check if the circuit is working properly, if it's your problem is temperature and probably the type of cmos used, check datasheet to see the level of "1" or "0" necessary in the inputs;

If without it still not working, you have bad connection, check each input level voltage and see if the output is correct see logic table.