tl;dr – the schematic
A new approach to a timed recorder
For the last year or so I’ve been trying to make an timed start recorder using a Raspberry Pi and the Wolfson/Cirrus audio card. I was able to make it work, but never eliminate some rattiness in terms of overruns on record – I confess I couldn’t hear them, but it didn’t give me a good feeling. Then I added up the costs –
£25 – Cirrus Audio card
£27 – Raspberry Pi B+£10 – case and odds and sods to make it work
£20 – PCB, time and bits to make a preamp to get from mic to line level
so I’m looking at £80 to get off the ground, and that gives me a seriously power-hungry SD audio recorder, although I can use a timer to save the power drain for active service.
Alternatively, if I could crack the remote control for them I could go on ebay and get a secondhand Olympus LS10, or one of the similar models (LS-5, LS-11, LS-12, LS-14) and use my own LS10 to start with. I can feed a mic straight into the LS10, no extra preamp required and the audio spec is good.
Reverse engineering the Olympus remote control protocol
This cost me £90 on ebay, and it turned out I didn’t need it. You get the info for free, but then I got a natty nearly new LS-14 with an RS30 remote control, so I’m not too unhappy. Unfortunately the RS30 doesn’t work with my Olympus LS10, don’t know why. I’d have been hacked off if I’d just got the RS301. Works a treat with the LS14 it came with, on their own a RS30 seems to go for £50, so I got an okay deal.
Google first – I owe dashanna of the naturerecordists’ list for inspiration, I vaguely recall seeing that post go through on the list. Their solution is this
The connector is an evil little 2.5mm four-pole jack, and these are a bear to solder
I can’t help wondering if life would be easier using a three-pole jack, since only sleeve and ring are needed. Now I didn’t like that battery in dashanna’s version – I mean who the heck would make a wired remote for a machine offering you a 3.3V supply on the tip of the plug and demand you go fit a battery in your remote? It’s just not a clean engineering solution at all. But apparently it works.
So I rigged the cable in series with the RS30 and sniffed the signals. Of the TRRS the tip had 3.3V, the second ring seemed open circuit, the first ring had the wanted signal and the sleeve was ground. Presumably the IR receiver and LED driver are powered off the 3.3V on tip. The signal on the first ring rests high at 3.3V.
In practice you can ignore the second pulse. For all I know it could be an ack back to the receiver to light the LED. I tried using a couple of diodes to pull the signal down to 1.2V but that didn’t initialise record. I then figured this is one of those analogue resistor chain remotes, so I look for what resistor would give me ~1.5V. Turns out if you replace the 1.5V battery in dashanna’s schematic with 100k you get about 1.5V and the recorder starts recording. You don’t need the second pulse at all, and the debouncing seems to be done in the recorder, it takes a little while, up to about half a second to start recording. I guess that means inside the recorder there’s a 100k resistor to the 3.3V rail in series with the first ring.
That works with both the LS 10 and the new LS14, although the RS30 only works with the LS14. So now all I need do is mod the timer to pull down a couple of pins, one through 100k. If I make the stop command the open-drain pin to ring and the rec command a normal pin resting High via 100k to ring, and pull the relevant pin down for 100ms I should be good to go.
- I’ve just got onto the Olympus RS30 website and if you scroll through the models that is compatible with it includes the LS-3, LS-5, LS-11, LS-12, LS14, LS-20M, LS100 so perhaps my LS10 was never compatible with it and Olympus have changed their mind since writing the LS10 manual which says on p65 “Exclusive remote control RS30W (scheduled for Spring 2008)” ↩
Thanks!
This is EXACTLY what I was looking for – a WIRED remote solution replacing the expensive and unreliable RS30W by OLYMPUS!
The linked RS30W page seems to suppress several compatible devices, e.g. my own LS20-M is not mentioned either. Although the remote is explicitly mentioned as an option in my user guide like in your LS10.
All my inquires at OLYMPUS, FixYa and forums did not get answered, eventually a good soul at Amazon ponted me in your direction, perfect!
I am awating a M2.5mm to F3.5mm converter so I can solder the needed wires more easily on a larger 3.5mm 4 pin plug.
If I understand your description correctly the R1 (next to the sleeve S) is ‘floating’ high and needs to be pulled to lower voltage, like 1.5V, for START, and to full GND for STOP, right? And R2 (next to the tip T) has no function at all? How odd is this, why did they use 4 pins in the first place?
The resistor method appears to be the best solution in this case, can’t wait to get my plugs so I can test this method. I did not dare to tinker with all 4 pins by ‘trial and error’, not knowing if the supplied voltage at T may be damaging the unknown remote input line(s) at R1/2
While the LS-20M is a cool cat the missing wired remote (or a REAL remote with ALL functions) is a definite setback. As is the tele lens (for that I found my own hack by mounting a tiny 0.6x ‘fisheye’ lens for smartphones to the front of my LS-20M!).
It’s a hacker’s world I guess…
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It was dashanna who did the legwork. I just couldn’t stand that battery. The fewer battery-powered gizmos you need working together in the field the better life is IMO 😉
Just pull Ring 1 next to the sleeve to ground via 100k to record (you’ll get 1.5V on the ring 1 at that stage), and once you’re done pull it down to ground via a short to stop. You need at least 100ms. Works just fiddling around with bare wires so I guessed debounce is already in the recorder.
I rigged a PIC micro to do this job and it works fine, with one pin via 100k and the other set to low and toggle between HiZ input and Lo-Z output. Pulse one or the other for 100ms, job done.
The second short pulse is indeed an ack back, since I observe that with my rig though I’m doing nothing to initiate it, or to use it.
I did try trial and error on my LS10 and perhaps I trashed the 3.3V supply on tip, which isn’t there when I measure it so that’s one good reason the RS30 doesn’t work on it. The wired version works dandy on the LS10 and same on the LS14, either with switches or with the PIC microcontroller
I couldn’t determine any signal or function on the second ring. But once I got the functionality I wanted I quit investigating it. I’m not saying categorically it does nothing 😉
Me again, with rather disturbing news:
indeed the LS-20M does react on the remote port to these switches between S and the adjacent R, but in a rather unreliable way.
Apparently the ‘timing’ of the pulses is critical, often the press of the START button will NOT activate the recorder. I tried short quick and longer presses to emulate these 100msec, with mixed results.
In general I can trigger the STOP function more easily by simply repeating the GND connection several times by the switch.
For the START pulse I tried different resistors (down to about 1k) and also 3.3V pulses from the tip, out of curiosity.
In fact there was more reliability of START when using lower R values and the forced pullup voltage from the tip.
In many cases a pulse would cause a switch of the display (different screen), but NOT a start of the recording, very odd..
Precise ‘pulse switches’ that trigger short signals by themselves when ‘clicked’ would probably help here.
This is all rather unsettling; I really need a reliable way to start and stop the recordings, as I can not ‘see’ the reaction of the recorder at that time, have to rely on its proper reaction.
Paying the demanded $60 for the crappy IR remote is the last thing I will do.
I’d rather sell this Olympus LS-20M toy and get a SONY HDR MV1 instead.
Just too many shortcomings as to the optics (needing their own ‘hack’) and this remote control issue.
The LS-20M is a weird device, just as weird as it looks.
I guess there’s some possibility the LS-20 responds differently from the LS-14 (and my old LS10). Although in the initial experiments I simply tapped a couple of wires together, my interest is in a timer delay, so I used a PIC, using two pins of the PIC as described to give the timer output for start and stop.
The timer works fine, but then I can guarantee a nominal 100ms pulse length without glitches. That works every time for me, so I guess putting a PIC in to clean up your switches would do. Or go the old-skool way using a CMOS CD4538 dual monostable set to nonretriggerable and a 100ms delay to drive a NPN transistor pulldown via about 10k – the collector current is so low so the saturation voltage is low enough. You could use one half for each switch, which would give you a defined and clean pulse duration.
Seems like this can perhaps be done in a more simple fashion – at least for the LS-10 it appears:
http://bioacoustics.cse.unsw.edu.au/archives/html/naturerecordists/2012-01/msg00058.html
and indeed I name-checked dashanna’s original post and schematic 😉 It was the extra battery I didn’t like. The top schematic is the manual wired remote version of his design without that 1.5V battery.
Fantastic, thanks for this: exactly what I was looking for.
I’ll do my own tests when I can get a 2.5mm TRRS jack, but you don’t happen to know off hand if it works ok pulling ring 1 to ground through 1k instead of through a short for the STOP? I’d worry about sinking too much current through the short, and 1k should look pretty much like a short to the LS14 anyway if it’s normally looking for 100k…
I don’t have the right cable to hand at the moment – the easiest way I found to interface this is to get a 2.5mm TRRS to 3.5mm TRRS cable on ebay and use a 3.5MM TRRS socket and the cable is in service at the mo. That way you but the control circuit in a box with a socket and the cable saves you making one up and going crosseyed at the 4-pole plug.
I got away with the NPN transistor when I was messing around and VCE on was extremely low – nothing like the usual 0.3V. So I’d give it a go – after all 1k will give you a voltage of .033 V.
What a lucky find!
I have an Olympus LS14, which I primarily use for nature recording. I had been eyeing up the infrared remotes, and baulking at the price of them. Since I’m already tethered to the recorder as I monitor using headphones, a DIY wired remote seems just what I am looking for.
Will order up the required components, and put one together. Nothing worse than a recording getting spoiled with the sound of the record button on the device getting pressed.
Hi Richard,
thanks for the inspiration. I have an LS-12 and just made the first tests with the remote REC&STOP.
I can confirm STOP is the electrical short of the first two connectors near to the cable end.
REC will work using the battery supply from the LS-12. So I used two resistors 6K8 Ohms (probably 10 KOhms will also work) in serial between 1st and 4th connector. Then using the middle between both resistors (to get around 1.5Volts out of 3 Volts available) to trigger 2nd connector to start the recorder.
Will use two foot switches to trigger the both functions to record my saxophone trails. Can post also pics if I finalized this process.
Greetings from Germany , Best Regards Patrik
> So I used two resistors 6K8 Ohms (probably 10 KOhms will also work) in serial between 1st and 4th connector.
That’s an interesting way to get the half voltage 😉 But it’s fair enough – I came to the conclusion using 100k from 3 to ground worked, but your approach is also good!
Hi,
I just came across this post and wondered if you could help, I have an LS-10 which doesn’t work reliably now for some reason, it has been stored for a few months without batteries. I think it may need a clean inside, is there a service manual available, I’m not sure how to take the covers off and don’t want to risk breaking anything. I know this is nothing to do with your post but would be grateful for any help.
Kind Regards,
Nigel.
> I’m not sure how to take the covers off and don’t want to risk breaking anything
I never found a service manual for it, but I have had mine apart and back together again, though the fault turned out to be a broken mic cable. It was a while ago and this is from memory, but using a jeweller’s screwdriver take the screws out of the back and ISTR the sides, then a spudger or a fingernail or a credit card to ease off the back. There are ribbon cables running all over the place particularly the display.