Simplest circuit to connect/diconnect a wire.

[ebastler]

@ebastler Its the HC-SR501.

The schematics floating around on the net (e.g. http://www.netzmafia.de/skripten/hardware/RasPi/Projekt-PIR/index.html) show a 1 kOhm series resistor in the digital output. The whole PIR circuit is powered by 3.3V, via an on-board regulator. So you can't pull more than 1mA or so from that output. Your dual-stage transistor circuit seems like the way to go.

[soldar]

Like in many treads here, the major part of the problem is trying to figure out what the OP is trying to do. I am not even going to try because there are many posts which would need much de-confusing.

I do want to present something I have done in the past and I believe it is an idea which may be useful to others. I have used it with PIR detectors but can be used with anything which changes its current consumption when it changes state.  This circuit detects the increase in current consumption and activates a transistor which can be used to activate a relay or anything else.

The main advantage is that I don't need to get into the circuit as I only monitor the current consumption as it goes into the circuit being monitored.

[ebastler]

Like in many treads here, the major part of the problem is trying to figure out what the OP is trying to do. I am not even going to try because there are many posts which would need much de-confusing.

I think the OP has made his intent pretty clear. He wants the PIR to trigger his (existing) wireless doorbell. The mechanical switch to the doorbell should remain functional too:

I have a wireless doorbell.  Its switch shorts Vcc with some other point in the circuit.
I also have a PIR sensor with a 3.3V control signal.

What I want is a circuit that when the PIR control signal is high, it will short Vcc with the
other point on the circuit.  Like pressing the button, so the wireless doorbell will chime
with motion as well.