I have the emitter of the transistor connected to ground, the collector connected to the 3v signal line of the device I'm trying to trigger and the output from the AMN connected to the base.
Any suggestions for what I'm missing?
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jeffcraighead wrote:Any suggestions for what I'm missing?A schematic or some wiring diagram that "we" can look at. For example what do you have for a base resistor ? Is the device you're connecting this to amenable to an open collector type output ? Do you need a pull-up resistor on that output ?
IdahoMan wrote: I'm a noob and don't fully know what all the acronyms mean, but I think I get the idea. On the output voltage though, what does "Vdd-0.5V" mean?Vdd is the PIR's supply voltage, 3-6 vdc. So the spec means that when it's detecting the sensor output is somewhere between the supply voltage and the supply voltage - 0.5v.
IdahoMan wrote:It's a security project for in-the-field surveillance. The picture below shows the point I am at. Assuming the terminals on the DVR have a proper voltage, could I rig it as shown?Nope. The PIR output a +voltage when detecting and the DVR trigger input wants a ground to trigger the DVR.
IdahoMan wrote:If not, I guess I would have to use some kind of means to drop the voltage down from the main source to 5v and then rig some kind of PIR/Transistor/Relay correct?That's right. You need a voltage regulator to make 5v (?or maybe 3.3v?) from the ~12v battery. Then a simple transistor circuit (or relay) the "invert" the sense of the PIR output.
IdahoMan wrote: Let's say we have 3.33v to work with at the "A-In" and "GND". The objective is to close these two. How would I do that with a transistor? GND to E, A-In to C? Then just need a way to add a little "+" to the base, yes?From your measurement I'll say the A-In has some pull-up resistor to it's regulated Vcc (3.3v). That makes it easier. So let me amend my instructions above.
Mee_n_Mac wrote:The picture below shows the amended diagram as you described.IdahoMan wrote:RE: your circuit - You need remove the hard wire between the PIR output and the transistor's base and replace it with a 1kohm resistor between the PIR output and base. And then remove the connection between the PIR Vdd and the transistor's collector. Leave the collector connected to A-In. Keep the ground connections as you have them. This will make an open collector driver.
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