Guest 89Panadol Posted September 13, 2009 Report Share Posted September 13, 2009 How to use a BJT as a switch...I want 2 connected the alarm circuit and UltraSonic Radar...please anyone tell me.. Quote Link to comment Share on other sites More sharing options...
www.electronworks.co.uk Posted September 13, 2009 Report Share Posted September 13, 2009 get two pnp transistors. connect their emitters together and connect these to the power input. Drive the bases low via a 10k resistor. Take the outputs from each collector.Once again, your posts do not make a lot of sense. If you used proper English, you might get more help.At a guess, I think the above answers your question. Quote Link to comment Share on other sites More sharing options...
Guest 89Panadol Posted September 13, 2009 Report Share Posted September 13, 2009 oo..then i connected the alarm circuit to the collector.... Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 13, 2009 Report Share Posted September 13, 2009 The ultrasonic Radar circuit is not Radar and is not Sonar. It is a simple motion detector with a short range.It has a transistor output to activate an alarm but I don't know which alarm circuit you have. Quote Link to comment Share on other sites More sharing options...
Guest 89Panadol Posted September 14, 2009 Report Share Posted September 14, 2009 i get the alarm circuit from this websitehttp://www.redcircuits.com/Page84.htmhow i can connect it to the Ultrasonic radar... Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 14, 2009 Report Share Posted September 14, 2009 The two projects are connected together like this: Quote Link to comment Share on other sites More sharing options...
Guest 89Panadol Posted September 17, 2009 Report Share Posted September 17, 2009 ooo thank you very much....now i understand how to connect the circuit...and congratulation for fast reply and your help....yahoooo.. ;D ;D Quote Link to comment Share on other sites More sharing options...
Guest 89Panadol Posted September 21, 2009 Report Share Posted September 21, 2009 Is it really work if connected like that.. Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 21, 2009 Report Share Posted September 21, 2009 Is it really work if connected like that..Yes.TR1 will turn on and it will turn on the alarm circuit. Quote Link to comment Share on other sites More sharing options...
Guest 89Panadol Posted September 25, 2009 Report Share Posted September 25, 2009 how about the IC 741 OPAMP...Could i change it like your advice in other forum.. Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 25, 2009 Report Share Posted September 25, 2009 how about the IC 741 OPAMP...Could i change it like your advice in other forum..The very old circuit already had its extremely old opamp changed to a 741 opamp. The first opamp needed C3 but the 741 opamp does not need C3.I would use inexpensive, low noise and wide bandwidth TL071 opamps in this project. Quote Link to comment Share on other sites More sharing options...
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