Quorum PIR sensor and cheapo MP3 player

[Otaku]

Hi all,
A lot of us now have a bunch of the cheapo MP3 players and some are probably thinking "How can I control this thing to play when I want it to and then shut down? And how do I do it on the cheap?". Here's a way to do just that.
The PIR unit has a 2 sec. 9VDC output when it sees a heat source. This can be used to power a relay that is used to short the Start button of the player. As it turns out, 2 secs is just what's needed to start up the player. With a minor modification to the timer board that is documented in the PIR user manual, you can control the time that the player stays on, up to about 1:30. The additional parts to do this hack are a female USB-A connector, a AA battery holder, a PC-mount relay (SPST will do the job), and a small 2-pin connector to simplify attaching/removing the player module when you want to attach it to your computer. What you end up with is a stand-alone MP3 playback device that is triggered by the PIR sensor and timer-controlled.

You'll still want to do the 30/60 off interval modification. This is covered in the how-to that is posted on FE's site. I also cover the build of the timer board. If anyone is interested in doing this hack, let me know and I'll work up a how-to.

[joker]

I'm definately intersted in a how-to. Would it be possible to trigger say 3 mp3 players simultaneously from one PIR?

Would be great to have my Zombietronix audio start after someone enters the room as opposed to already playing when they come in.

[Otaku]

Sure, more than one can be triggered, but you may need to beef up the AA battery pack to a 4AA (1.5 volt output) or a 1.5VDC regulated wall wart so you don't run out of power.

[Bilbo]

Otaku, any chance of you moving to Duluth, MN to become my personal electronic guru?

[Otaku]

Probably not, I like sunny California too much!

[Mazz]

I know I sure could use a how to on this hack.

[Otaku]

I built a prototype board today to test this hack, and so far so good. I'll test it with an MP3 player module tomorrow to see if it starts the player correctly. I'll get some pics with callouts posted soon. This board will also work with any power source that can deliver a 2 sec. 9VDC pulse, and the Quorum PIR is perfectly suited for this. The pulse can be longer than 2 secs. but the player will not start until the power is cut and the relay switches.

[Otaku]

I'm definately intersted in a how-to. Would it be possible to trigger say 3 mp3 players simultaneously from one PIR?

Would be great to have my Zombietronix audio start after someone enters the room as opposed to already playing when they come in.

Joker, the only caveat here is that the time would have to be set to allow the longest file to finish playing. You'd need to add silence to the ends of shorter files to match that length in order to prevent the looping feature from re-starting the other players. The max play time right now is ~1:30, but could be increased by changing a resistor or the pot value. To trigger multiple players, you'd wire the Start buttons on the players in series with the "start" relay.

[Otaku]

The Darlingtons I needed arrived today, so I'll continue with the build in the morning. More to come...

[Otaku]

OK, so I built out the board with the Darlington transistors and found that there's too much of a voltage drop across the transistor to operate the player. The drop is about .3VDC but that's enough to prevent the player from running. The 2 sec. pulse, however, is sufficient to get the player to start. I'm going to use a 9 volt battery, a 5VDC fixed regulator and a voltage divider to get to the required 1.5VDC for the player. It's bit more complicated, but easy to put together. I may also try using a FET to switch power (in place of the Darlington), but I'm not sure if the same voltage drop issue would come up again. Bottom line - this hack will allow control of the MP3 using the PIR sensor. More to come...

[Koumajutsu]

FET should work, when biased properly they produce nearly no voltage drop.
It's one of the reasons I don't bother with traditional transistors anymore.

[Otaku]

Whew! With the generous assistance of Kouma and gmacted, the circuit is finally working. I replaced the Darlington with a FET and the voltage drop issue is solved. The Quorum PIR sensor and modified R/C timer board lets you control the MP3 player. As per the MP3 hack I did last year, you need to attach trigger wires to the player Start button so the 2 sec. pulse from the sensor will start the player. I also recommend doing the 30/60 sec "off interval" hack on the PIR, otherwise you're stuck with 15 secs. or 15 mins. as the reset times. I'll get a circuit drawing up in the next few days. Again, my thanks to Kouma and gmacted for their guidance.

[Otaku]

Some test results - the max time for playback is 2 mins. if you max out the 1M pot. However, the max time between resets on the PIR is 60 sec., so if the PIR is triggered during the playback period, the player will be turned off. I use these players for fairly short sound files, no more than 15-20 secs so its not an issue, but if you need more than 60 secs, this won't work for you.

[Koumajutsu]

More than 60 seconds would be doable with some changes to how the PIR mod is done.
Specificaly, those two jumpers across that chip could be moved to different uncut pins to produce different times, though always multiples or divisions of the original times (i.e. 2 minutes, or even 15 seconds)

[Otaku]

True, the original times were 15 secs and 15 mins. I could look up the datasheet for the ripple timer and identify the pins for various times. I should probably do that for those who want to hack the PIR but would prefer off times other than 30 or 60 secs.

[Koumajutsu]

here's a pinout from the datasheet with the times from the original marked, the pins from the how to, and some other pins marked.

however as i was going through it, the math began to break down rather quickly.

I think some experementation may be in order

I ordered 4 of these sensors last night, when I get them, I'll pick through the circuit with a fine toothed oscilloscope and try to get some accurate timing information for you Otaku.

cheers

[Koumajutsu]

Just checked my tracking number, and I'm expecting my toys to arrive today, I'll take them to work with me tomorrow and reverse engineer the thing :D

[Otaku]

Cool. Thanks - this should yield some interesting info.

[Koumajutsu]

OK, I managed to find out a good bit about this little toy.

1) the thing is dependant on an RC (resistor-capacitor for those non-techies) time constant for the reset frequency.
-What this means:
Near that chip marked MC14060 there are 2 resistors and a capacitor (the resistors are on the bottom) that can be replaced with different values to obtain different times.
-Difficulty: Intermediate

2) This RC thing means that every PIR will be slightly different in timing so don't expect precision out of this thing.
I have attached the times for each of the pins on the unit I disassembled. your's may vary
-Difficulty: Same as original hack

3) If all else fails, you can control the reset time directly by not using the time select jumper and connecting your own 5 volt logic signal into the center pin (+5 to hold it in reset, 0v to allow it to trigger) This is with reference to the battery terminal marked GND

this can also be done with a relay or FET to connect pin 11 of the 4060 chip shorting it to ground when you dont want the timer to run. (with this setup, after you open the relay, or denergize the FET, the PIR will start it's timing and be able to retrigger after you re-enable it + the timeout)
-Difficulty: Advanced

[Otaku]

Fascinating stuff. Item 3 definitely answers a question for me. Thanks for the info, Kouma!

[Koumajutsu]

oh, there's much more to be learned about this thing, I only spent about 20 minutes messing with it today. (I was kinda busy at work)