Relay connection

[ericgibbs]

Hi Mr Gibbs,
I have found the short the was causing the fuses to blow.I have another problem.the circuit does not reset nor will the beeper stop beeping continiuosly...i have tested it without the ac applied to the relay contacts...the relay is always energized when the i apply supply to the circuit keeping the beeper on.what could be the problem?

hi,
You could have blown the 2N2222.
Disconnect R5 from the 4011 output, that goes to the transistor Base, connect the free end of R5 to 0V [ so thats the Base to 0V via R5]
The relay should not energise, if it does, the 2N2222 could be shorted or you have wiring error on the relay coil connections.

Lets know what see.

 

[Christy]

Hi there, i will give it a try.but i see u have mensioned 4011,but your circuit diagram mensions 4024...is there maybe a problem with using 4024?

 

[ericgibbs]

Hi there, i will give it a try.but i see u have mensioned 4011,but your circuit diagram mensions 4024...is there maybe a problem with using 4024?

Sorry about that a typo its CD4093.....the quad NAND gate.

 

[Christy]

No problem sir,will try your method of troubleshooting and see what is the cause.

 

[ericgibbs]

No problem sir,will try your method of troubleshooting and see what is the cause.

What value of C2 [ near the 555] are you using.???

 

[Christy]

220uF...They one minute time interval I wanted is working,i put a LED on the output pin of the 555 to see it.

 

[ericgibbs]

220uF...They one minute time interval I wanted is working,i put a LED on the output pin of the 555 to see it.

hi,
I asked just in case you had used a very low value that would make the output 'appear' to be ON all the time.

 

[Christy]

Hi there,
Thanks for the concern Mr Gibbs.