C cannibal New Member Dec 5, 2007 #1 Hello I have circuit which was working perfect in the breadboard the circuit is attached like it is when was working when I made PCB and moved all the parts the buzzer is making non stop sound I don't know where is the problem could you please check my pcb to see if I made some connection wrong !! I checked the soldring and nothing touchs please help Attachments 1pbb.GIF 15.9 KB · Views: 128 2pbb.GIF 12.7 KB · Views: 110
Hello I have circuit which was working perfect in the breadboard the circuit is attached like it is when was working when I made PCB and moved all the parts the buzzer is making non stop sound I don't know where is the problem could you please check my pcb to see if I made some connection wrong !! I checked the soldring and nothing touchs please help
audioguru Well-Known Member Most Helpful Member Dec 5, 2007 #2 If the transistors are BC337 then the pcb for the 555 and transistors is the same as the schematic. Like I said in the thread about this circuit, the 555 will never time out if one LDR is in the dark. Then the buzzer won't stop. The pin 2 trigger pin of the 555 must be pulsed through a coupling capacitor then pulled up with a resistor to correct it.
If the transistors are BC337 then the pcb for the 555 and transistors is the same as the schematic. Like I said in the thread about this circuit, the 555 will never time out if one LDR is in the dark. Then the buzzer won't stop. The pin 2 trigger pin of the 555 must be pulsed through a coupling capacitor then pulled up with a resistor to correct it.
C cannibal New Member Dec 5, 2007 #3 audioguru said: the 555 will never time out if one LDR is in the dark. Then the buzzer won't stop. Click to expand... yes that feature is needed (the 555 won't time out if one LDR is in the dark) if the PCB is correct why you think the buzzer won't stop like in the breadboard ??!! do I have to replace the 555 or the transistors ??!!
audioguru said: the 555 will never time out if one LDR is in the dark. Then the buzzer won't stop. Click to expand... yes that feature is needed (the 555 won't time out if one LDR is in the dark) if the PCB is correct why you think the buzzer won't stop like in the breadboard ??!! do I have to replace the 555 or the transistors ??!!
C cannibal New Member Dec 5, 2007 #4 I was double chacking the circuit and I found that R4 is brown black yellow it should be 100K but in multimeter it shows only 9K do you think that R4 is the problem that maks buzzer not stoping ?!
I was double chacking the circuit and I found that R4 is brown black yellow it should be 100K but in multimeter it shows only 9K do you think that R4 is the problem that maks buzzer not stoping ?!
audioguru Well-Known Member Most Helpful Member Dec 5, 2007 #5 cannibal said: R4 is brown black yellow it should be 100K but in multimeter it shows only 9K do you think that R4 is the problem that maks buzzer not stoping ?! Click to expand... A very bright light (sunlight?) might be needed to overcome the 9k resistor to turn off its transistor.
cannibal said: R4 is brown black yellow it should be 100K but in multimeter it shows only 9K do you think that R4 is the problem that maks buzzer not stoping ?! Click to expand... A very bright light (sunlight?) might be needed to overcome the 9k resistor to turn off its transistor.
K kchriste New Member Forum Supporter Dec 5, 2007 #6 cannibal said: R4 is brown black yellow it should be 100K but in multimeter it shows only 9K do you think that R4 is the problem that maks buzzer not stoping ?! Click to expand... You can't accurately measure R4 in circuit. Disconnect at least one end of R4 first before ohm metering it.
cannibal said: R4 is brown black yellow it should be 100K but in multimeter it shows only 9K do you think that R4 is the problem that maks buzzer not stoping ?! Click to expand... You can't accurately measure R4 in circuit. Disconnect at least one end of R4 first before ohm metering it.
C cannibal New Member Dec 5, 2007 #7 Wow problem solved 100k defected one which shows 9K has been replaced with new 100K thank you again