How to modify a Quorum PIR By Gary Adams on the Unpleasant Street Fourms to allow two off-interval times, 30 and 60 seconds between triggers. The timer can be set from 2 seconds to 1:30. The total cost is under $18, including the batteries. Parts list at the bottom of the page.


Step 1: Cut pins 3 and 4 on the timer chip. Be careful to not damage the chip. Bend the remaining tab on the board to form a solder pad.

Step 2: Cut 2 wires about 2" in length. I used 30 gauge stranded wire, but any small gauge wire will work. Strip and tin the ends and the cut tabs with solder. Solder the two wires to the tabs that are left on the board, not the tabs on the chip. Be sure that the solder doesn't bridge to anything else.

Step 3: Solder the other ends of the wires as shown on the other side of the chip. These two pins have output times of 30 seconds and 60 seconds. When the jumper tab is in the position shown in this picture, the "off" time will be 60 seconds.

I used a single LED with a 330 ohm resistor to test the circuit. Notice the two black wires in the first pic - those are the outputs that you'll connect to the timer board later. Right now they can be used to test the timing.

Step 4: Solder wires to the off-time interval pins. These wires should be about 5" long. Solder two wires to the board as specified in the instructions you got with the PIR. These are the wires on the right in this picture (I replaced the two black wires in the previous pic). They will connect to the timer board.

Step 5: Drill holes in the back of the case as shown. These are for the power on-off and trigger interval switches. Measure the threaded part of the switch to determine the drill size.

Step 6: Install the switches as shown.

Step 7: Solder the trigger interval wires to the switch. The upper black wire in this picture is the 30 second interval wire.

Step 8: Solder the wires and external battery clip to the snap on the PIR board. Be sure to keep the battery polarity correct. The two black wires are soldered to the lower and center terminals on the power switch.

Step 9: Label the switches (optional, but helpful).

That's it for the PIR hack. You now have a power on-off switch, external battery access, and the ability to set the trigger interval to either 30 seconds or 60.

All Electronics:
Part / part number

Switch - MTS-4
Cost 4/4.00
Qty. needed 2
Ext. cost 2.00

Relay - RLY-645
Cost 1.50
Qty. needed 1
Ext. cost 1.50

Perf board - PC-3
Cost 1.50
Qty. needed 1
Ext. cost 1.50

Cost 5/.50
Qty. needed 1
Ext. cost 0.10

Capacitor-100mfd/35V radial
Cost .27
Qty. needed 1
Ext. cost 0.27

Diode - 1N4148
Cost 15/.99
Qty. needed 1
Ext. cost 0.07

Potentiometer - AP-1M
Cost 0.50
Qty. needed 1
Ext. cost 0.50

Resistor - 470K ohm 1/4 watt
Cost 10/.50
Qty. needed 1
Ext. cost 0.05

Resistor - 1K ohm 1/4 watt
Cost 10/.50
Qty. needed 1
Ext. cost 0.05

Project box - TB-3
Cost 2.50
Qty. needed 2.50
Ext. cost 2.50

Term. strip - TS-206
Cost 1.58
Qty. needed 1
Ext. cost 1.58

9 volt battery snap - BST-3
Cost 4/1.00
Qty. needed 2
Ext. cost 0.50

Electronic Goldmine:

PIR sensor unit - G4567
Cost 5.95
Qty. needed 1
Ext. cost 5.95

Misc. stuff - estimated cost:

Solder 0.10

22 gauge wire 0.25

9 volt battery 2/.99 at Big Lots - 2 required


Timer Board


Step 1: You should have the following parts:

From All Electronics (part, p/n, qty):

Switch, MTS-4, 1 each

5VDC relay, RLY-645, 1 each

Perf board, PC-3, 1 each

Transistor, MPSA13, 1 each

100uF 35 volt capacitor, 1 each

Diode, 1N4148, 1 each

1 Megohm trimpot, AP-1M, 1 each

Resistor, 470K ohm, 1 each

Resistor, 1K ohm, 1 each

Enclosure, TB-3, 1 each

Terminal strip, TS-206, 1 each

9 volt battery snap, BST-3, 2 each

26 gauge wire

Some small screws for mounting parts

Important: Please read through all of the steps before starting.

Step 2: Pick a location near the center of the board to start attaching the parts. Attached are the positive power wire, the diode, the capacitor and one of the potentiometer wires. Note the diode ring direction. The negative side of the capacitor is facing to the right. Use solder bridges to connect the parts on the board.

Step 3: Attach the 470K resistor

Step 4: Attach the transistor. The flat side of the transistor is facing you in this pic.

The pins are named as follows: base (center pin), collector (right-hand pin), and emitter (left-hand pin). The base pin is connected to the 470K resistor.

Step 5: Attach the second potentiometer wire and the 1K resistor

Back view showing the solder bridges. The transistor is on the right. Leave two of the transistor pins long and bend the collector pin over to the right as shown. This will make it easier to solder it to the relay

Step 6: Attach a short wire from the emitter pin of the transistor to the 1K resistor.

Step 7: Connect the 1K resistor to the negative leg of the capacitor. I used a small piece of wire trimmed off of a resistor as a bridge.

Step 8: Attach the relay. You need to bend some of the pins a little as shown to get it to fit the board. Look on the bottom of the relay and you'll see a small rectangle between two of the pins. These are the coil pins.

Step 9: Here's the relay soldered in place. The two pins top to bottom are: the Common pins, the coil pins, the Normally Closed pins and the Normally Open pins. Notice the power negative wire has been soldered in beside the 1K resistor. Again, I used a piece of wire cut off of a resistor as a bridge to connect the relay to the transistor.

Step 10: Top view of the board. The two black wires that are close together will be soldered to the potentiometer.

Step 11: Solder the wires to the relay pins. The wires should be about 6" long. White wires are Commons, red are Normally Closed and black are Normally Open.

Step 12: Attach the terminal strip. Mark and drill two small holes for the strip. Notice the holes just above the edge of the strip in the second pic- these are for pulling the relay wires.

Step 12: Drill the hole for the potentiometer. Also drill a small hole for the power wires to come out. Drill a similar small hole on the opposite side of the box for the battery leads.

Step 13: Solder the wires to the pot. Use the center pin and either outside pin. Reference Step 10 for the correct wires.

Step 14: Attach the pot to the box.

Step 15: Bring the relay wires through the holes and screw them to the strip.

Step 16: Attach the board to the box. Here's what it should look like.

Step 17: Solder the battery snap as shown. Polarity matters here - be sure the wiring is correct. The red battery wire goes to the relay coil pin, and the black wire goes to ground.

Test the timer by attaching a battery to the clip. Use a second battery to simulate the pulse from the PIR. Turn the pot all the way to one side. Touch the black (-) and white (+) wires to the battery terminals for a couple of seconds. You should hear the relay click. Depending on which position the pot is in, the relay will either quickly click again or will wait about 90 seconds. If you have a DMM, you can monitor the voltage drop on the capacitor. The relay disengages at ~1.5VDC.

You're done. Connect the two wires from the back of the PIR to the wires on the timer and start playing with various settings. If you have any questions, email me at Include pix if you can.