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Can anyone help me with the attached schematic, I don't really understand were the line of " VREF" connects to , maybe I can not see the trees for the forest!

9v

cheers

spikeVelleman MK 120 Hi

Thank you all , for all your replies, I have tried to do a schematic that I can understand from the schematic I first put on here, would anyone be able to have the time and patience to check it out!

Cheers and again thanks, what a great site, and nice people willing to help people like me that are very new to electronics.

spike

enter image description here

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  • \$\begingroup\$ I am not a school child , I don't need anyone changing or altering my wording . \$\endgroup\$ – Spike1947 Apr 11 '16 at 18:42
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Vref is generated by IC1D, and it serves as a DC bias for all other stages, so they can work with ac coupled signals.

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  • \$\begingroup\$ Thanks for that info , do I take it that 14 , 3 , and 5 of the IC LM324 are linked together ! , and were does COMP link to ! , sorry for all the questions I am just a newbie .chhers spike \$\endgroup\$ – Spike1947 Apr 10 '16 at 8:55
  • \$\begingroup\$ No problem, yes you should take it as an internal connection, it is just to avoid having a wire line going all through the schematic. Comp goes from C3 to the inverting input of IC1C, which is acting as a comparator. \$\endgroup\$ – payala Apr 10 '16 at 9:03
  • \$\begingroup\$ Thanks all , for your replies , there is just one more problem with this schemtic , that is the time period when activating the alarm is very short , is there a way of increasing the time on to the alarm ! .cheers spike \$\endgroup\$ – Spike1947 Apr 10 '16 at 9:41
  • \$\begingroup\$ I would say increasing C3 value should give a longer time to detection. But I'm not sure how much time you are thinking about, you could require something different. \$\endgroup\$ – payala Apr 10 '16 at 9:44
  • \$\begingroup\$ Hi , thanks for your reply , I am wanting to replace the Buzzer with a relay hopefully ( not sure of the current to the buzzer ) , so I would of thought about 3 seconds , I think this circuit is quite short maybe 1 second ! .cheers spike \$\endgroup\$ – Spike1947 Apr 10 '16 at 10:32

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