Brief History
V1 of the iPhone Call Recorder worked great but I found it suffered one issue after I published the post about it. I realized that the capacitors used to isolate the headphone and microphone needed to accumulate a bit of charge before they caused enough isolation to prevent talk back on the opposite end of the call. This meant that you needed to have a recording device plugged into the iPhone Call Recorder that puts out ~3 volts and both parties had to talk (to cause a charge to go through the caps) before the caps charged effectively. This really isn’t a big deal but I felt like it could be improved.
The [simple] Solution
I tried several other ways to try to accomplish what I was after but I mostly just ended up with a headache. From V1 this project was both incredibly frustrating and something that I just couldn’t let go of. What I kept coming back to was that the capacitors simply needed to be “pre-charged” but to do that required putting voltage into the system, not something I was keen on doing unless I could keep it from getting to the iPhone and the recording device.
The solution turned out to be quite simple:
Don't pay too much attention to this schematic... there are errors.
The design in pretty much the same as V1, except for the 9v battery, a couple 330 ohm resistors, an LED, power switch, and an additional capacitor. The battery pre-charges the two (primary) capacitors whilst an additional capacitor is used to keep the DC from passing out the recording output. The two primary capacitors isolate the mic and headphone (to prevent talk back) and also keep the DC from the 9v battery from getting to the iPhone. The 330 ohm resistor is used to knock the voltage down because having the full 9v going to the caps causes to much charge and completely blocks audio from the recording output.
The upshot to all this is that from the get-go the talk back problem is eliminated, even if you don’t have a recording device plugged in (or one that does not output voltage) there is no talk back. The one drawback is a slightly less punchy level on the recording output for the iPhone side of the conversation; I haven’t found this to be a big issue.
V2 Improvements and Features
- Improved talk back prevention – filter capacitors are now pre-charged via a 9v battery.
- Smaller (less fugly?) enclosure.
- Smaller and higher quality potentiometers.
- TRRS jack for iPhone compatible headsets – for instance you can use the ear buds that came with your iPhone to record a call.
- iPhone input is via a jack – Version 1 used a hacked TRRS cable coming out of the enclosure – this was inelegant and would make it difficult to repair if the cable was damaged.
- LED – ’cause LEDs make everything cooler.
- If the battery dies (or the switch isn’t turned on it functions the same as the V1 iPhone Call Recorder.
V2 Pictures
The following pictures are of a couple of V2 iPhone Call Recorders I made. The first one uses a small enclosure that is nice in that it has a battery compartment built in and is compact but its small size makes it difficult to work with. If you plan to make the iPhone Call Recorder V2 and you don’t have a lot of experience with electronics; I’d recommend using the alternate enclosure (noted in the parts table below) which offers a bit more room to work with.
This alternate enclosure is easier to work with than the one pictured previously. I like this enclosure better for that reason... and it's brushed aluminum and we all know brushed aluminum makes the world a better place.
Existing Options
Just to reiterate – Looking at my server logs I see thousands of Google searches related to recordign calls on the iPhone. I have no doubt that this is functionality people want built into the iPhone. People don’t want to have to use a bulky box and cables to do it, like me they want an app. Unfortunately, as far as I can tell there is no way for an app to be written that will record calls without the need for a third party (paid) service. It’s simply something that Apple hasn’t allowed, or for one reason or another, in their API.
There are two apps that I know of that facilitate recording calls on the iPhone – SpoofApp and Recorder 10:
- SpoofApp – In the time between my Version 1 Version 2 SpoofApp landed in the App Store and no longer requires a jail-broken iPhone. SpoofApp is a free app but you still need to purchase per-miniute credits in order to make any use of it. I briefly played with SpoofApp and it works well for recording outgoing calls.
- Recorder 10 – Available in the App Store for the low price of $0.99 but again, it only records outgoing calls and you have to pay per-min charge.
- Neither SpoofApp nor Recorder 10 lets you start a call recording mid-call.
- Both services require that your recorded phone calls sit on a third party server (privacy issue).
I would pay $50.00 for a native iPhone app that allowed on the fly recording of incoming and outgoing calls, saved the calls on the iPhone, and allowed for easy transfer of the recordings off iPhone. Unfortunately, it is my understanding that even if a developer wanted to, it’s not possible to interface with the iPhone during a call in such a way that would allow the recording of phone calls. For one reason or another Apple has not included APIs in the iPhone SDK to allow it. SpoofApp and Recorder 10 overcome this limitation by routing your call through a third party phone system which works, but has limitations.
Again, my solution is not perfect either, anything besides a native app is going to feel like a kludge. My solution is expensive, bulky, and requires basic soldering skills to make. However, it does surpass current apps in that it allows on the fly recording of incoming and outgoing calls and does not require you to pay per-miniute fees. It does what current apps can’t. Beyond the app I described, there is certainly room for improvement on a hardware solution, someone smarter and better equipped could make a hardware solution orders of magnitude better than mine.
DIY
I made a couple of V1 iPhone Call Recorders for people and a couple of V2s before publishing this and received dozens of requests for pre-made iPhone Call Recorders. However, most people lose interest really quickly when they find out it would cost them over a hundred bucks for one.
To be fair to myself, and the family I support, I have to charge for the time it takes me to assemble the iPhone Call Recorder. When you add all the costs up (parts, labor, shipping) a pre-made iPhone Call Recorder is expensive. For most I think this is a novelty item and they see some electronic bits thrown together by some guy in his garage (actually I’m in my house) and think it’s going to cost five bucks and get really sad when they find out it’s a lot more.
Besides that, It’s just not something I want to commit to at this point. I’d like to move on to other projects.
So, I’m not going to be taking requests for pre-made iPhone Call Recorders but what I have done is draw up a nice schematic and made a parts list complete with supplier links. I have tried to make it as easy as possible for you to get what you need to make your own iPhone Call Recorder V2. It does require that you have some basic electronics understanding and soldering silks (or a friend who does) but it never hurts to learn.
If you want to make one yourself, which I encourage you to do because making stuff is fun, I’ve posted a nice schematic and parts list with suppliers:
The Schematic
Here is the iPhone Call Recorder V2 Schematic drawn up in Visio [click to embiggen]:
For better resolution you can download the schematic as a PDF – here
The Parts
UPDATE – 04.26.2009: I have updated the parts list to reflect the parts that I use for pre-made iPhone Call Recorders and what I recommend you use if your going to DIY. The small black enclosure shown above is no longer listed because I recommend the larger (and easier to work with) aluminum enclosure. However, the part numbers for it and the custom perf board are: 546-1593PBK and 854-PR1593P respectively.
| Part | Supplier | Part # | Quantity (need/req) | Price (ea) | Total |
|---|---|---|---|---|---|
| TRRS Jack | Mouser | 161-5435-EX | 5 | $1.34 | $6.70 |
| Enclosure | Mouser | 546-1455J1201 | 1 | $16.90 | $16.90 |
| 9v Battery Holder | Mouser | 12BH095-GR | 1 | $0.30 | $0.30 |
| TRRS Cable | Digi-Key | CP-354S-M/M-ND | 1 | $6.66 | $6.66 |
| TRS Cable | Digi-Key | AE9918-ND | 1 | $3.76 | $3.76 |
| 10K POT | Digi-Key | 51AAD-B28-D15L-ND | 2 | $7.97 | $15.94 |
| 22uf 35v CAP | Digi-Key | P819-ND | 4 | $0.15 | $0.60 |
| 470 ohm Resistor | Digi-Key | P470BACT-ND | 10 | $0.08 | $0.78 |
| 330 ohm Resistor | Digi-Key | P330BACT-ND | 10 | $0.08 | $0.78 |
| 10k ohm Resistor | Digi-Key | 10KQBK-ND | 10 | $0.06 | $0.32 |
| Toggle Switch | Digi-Key | 360-1788-ND | 1 | $4.29 | $4.29 |
| Power LED | Digi-Key | C503B-BAN-CY0C0461-ND | 1 | $0.54 | $0.54 |
| Power LED Holder | Digi-Key | 67-1332-ND | 5 | $0.08 | $0.40 |
| POT Knob | Digi-Key | 226-3025-ND | 11 | $5.69 | $5.69 |
| 9v Battery | Digi-Key | N145-ND | 1 | $2.23 | $2.23 |
| 9v Battery Clip | Digi-Key | 377-1549-ND | 1 | $1.20 | $1.20 |
| Perf Board | Digi-Key | V2010-ND | 1 | $7.33 | $7.33 |
As always, if you have questions please leave a comment (preferred so others can benefit) or e-mail me at adam [at] awaitinginspiration.com.
If you make your own iPhone Call Recorder please, please, please, let me know and send me some pics.
I found version 1 while trying to find the pinouts for the headphone jack to connect my iPhone to Cisco’s Call Manager Express to play music-on-hold, so I don’t need this. But I wanted to say the amount of documentation for this is fantastic! The schematics are great, but the documentation of the parts and suppliers and prices is above and beyond what I usually see for a DIY project description on a website.
@Cisco Guy
Thanks! I am really trying to move in a direction of better documentation for the projects I do. It’s great when people share their projects but incredibly frustrating when there is no, or too little documentation.
Great writeup! I’m looking forward to digging out some of my rust circuit building skills and making one of these. But I do have one question, why did you decided to use TRRS jacks for all the connections? It seems like replacing them with regular headphone jacks would be cheaper. Of course, that would take away some of the sexiness of the final product.
@Patrick Wagstrom
Great send me some pics after your finished! I used the TRRS jacks for exactly the reason you mentioned. I do believe that the same manufacturer makes a TRS jack that looks like the TRRS jack but the cost is negligible if I remember correctly.
Hey man. I really want to buy one of these off you. Can I put the files to my computer after I record with your device? Let me know. Please email me.
Brilliant!
You sir, have inspired me to follow your plans and create one. I have never had experience in making electronic equipment, but there is no time like the present to learn. Failing at this, I may try to convince you to build one more just for myself. Yes, I am aware of your warnings on price and prepared for the price tag should I fail.
What are your thoughts on commercializing your product? Maybe pitch it to Appl themselves…
Thank you for your excellent documentation and shared knowledge.
High Regards,
Robert
@Jdubs
Yes you could put them onto your computer:
1. Use your computer as the recording device, that way there already on your computer. A bit bulky or impossible if you don’t have a laptop though.
2. Use a recording device (such as those little hand-held recorders) that has a USB port that will let you copy files off of the recorder to your computer. This is the best most portable way.
3. If the recording device does not have a USB port you could always just record your phone calls with it, then plug the recorder into the mic (or line-in) port on your computer and record it to your computer that way. This is obviously a bit time consuming because it would be recording to your computer in real-time.
@Robert
Dude really glad that your inspired to try making one yourself! If you do make one please send me pics!
As far as commercializing it… not likely. I know as well as anyone that that this is a kludge. It’s bulky and inelegant, I doubt Apple would be interested especially when they could just allow call recording to occur naively in the iPhone.
That said, I’ve moved on to other projects, but am still thinking of ways to improve the recorder. I may have come across a way to make the isolation better (would eliminate the capacitors) and thus make the whole thing smaller but I’m waiting for research funds to become available if ya know what I mean
H VRYBD…..f y bcm mmbr CG (Cnsmr mpwrmnt Grp), th wll gv y FR rd prt w t rcrd yr cnvrstns! wnt t [spam link removed] nd flld t fr fr Gns Gd n Hw T Rcrd Cll Phn Cnvrstns….WTHT XTR HRDWR!! Whn pd th $ mmbrshp, th snt m n ccss cd fr thr systm. cn rcrd p t hrs f n cnvrstn nd thn dwnld th .mp ff thr [chs] dwnld st. hv sd t sccssfll MN tms. Hp ths hlps ntl PPL chngs thngs!
Note from Adam – this comment apperes to be from a real person but is spammy so I disemvoweled it… more fun than deleting it.
Dude…..I didn’t spam you…???? do you have some login or something? Where is it. I was just telling people what I do. Ok..your site..
@Walter Montgomery
You are more than welcome to link to products/services as long as they are related to the post… the site you linked to didn’t appear to offer any services related to the iPhone or recording calls on it. In any case it hardly appeared legitimate.
Please see my comment policy at the bottom of this page.
ok, I understand. Well it definitely IS related. Fill out the form..I have a copy of the booklet in my hand. ..AND I have used the service to record my insurance company, my job human resources, Bank of america Mortgage, etc… I also love your project, as I am an electonics engineering tech! Should I repost the earlier info? Take care.
@Walter Montgomery
OK, I’ll go fill out the form that asked for a bunch of personal information, while I’m at it I’ll e-mail that Nigerian Prince my bank info so he can give me that billion dollars he said he wants to give me.
@Walter Montgomery
Got your last comment but Akismet flagged it as SPAM. This is important for you to understand because it means that you made a comment on a site(s) that uses Akismet for SPAM protection and the administrator of that site(s) flagged your comment as SPAM.
I didn’t flag any of your comments as SPAM because I was being nice but someone, on another site you commented on did.
The upshot – I’m not the only one who felt your comments were SPAM.
Do you have a diagram which instructs how and where on the enclosure to place holes for LED, pots, etc. I am inspired to build your device and have never done this before. I am pretty green but willing to try this. Your help would be appreciated. Thanks for taking the time to write a great instructional. Cheers!!
@Phil
Unfortunately I don’t… you can reference the pictures in the post to get a pretty good idea of where everything is placed though.
I must be missing something obvious here, but it seems that a major part of your engineering effort is dedicated to avoiding cross-talk between the microphone and speaker channels in your recorder. There are countless flash-based units which record in stereo – why not simply record the two channels independently and mix them later if required. This would allow you to do away with the mixer-box completely and create an adapter no larger than a cable splitter, which could be sealed in heat-shrink tubing.. I have seen both bluetooth headsets and in-car bluetooth handsfree adapters which have have duplex call-recording built right into the units. I still miss Callrec on my Treo/Centro – can’t beat having everything recorded automatically in files stamped with the time/date and caller ID.. *sigh*
PS: Luv the knobs, almost worth having a box just for those…
@Gordon
You are correct about the cross talk.
You are correct that you could split the mic input of the iPhone and headphone and push each one to a separate channel. The problem with this is that unless your recording device records in stereo, your not going to get both the mic and headphone.
Most of your handled digital recorders only record in mono, unless you get something spendy. I was more interested in a universal solution.
@Gordon
Those knobs are sexy.
All you guys on here f’n rule. I have no idea what half of this sh#t means, but I just spent the past 15 minutes reading it all and loving it. Thank you, and keep on nerding out for the rest of us dumb-asses out there. (no offence intended, I love nerds)
I have an app called CallRec.me and it has all the pitfalls of any ohter app… your system is by far the best solution. I’m jealous.
@Mark
Thanks. I plan to keep nerding out till I can’t nerd out no more.
@Mark,
too funny – i get some of it,, but not all. Adam is definitely a cool nerd…
@Adam,
will be looking forward to hearing from you
C
How about a dual blue tooth setup? One receiver for your head and the other for your recording device in your pocket. If they are on the same frequency, only one pairing should be required. This would fully conceal the recorder. The recording device could have a splitter on the mic input as well, allowing a second mic to record simultaneously so that both phone and live conversations can be recorded well without any switches.
H, thr s rcrdbl bltth hdst tht ds smthng lk tht n st [link to shit website removed by Adam] m thnkng bt rdrng n, bt nl rcrds mnts. Mght b ngh thgh.
@Walter Montgomery
Back again?
Listen, you tried to link to this page before and I removed it… I’m not sure what exactly you think has changed between now and then that makes you think it’s ok to post the same link again. Whatever Consumer Empowerment Group is, it isn’t legit.
The main page is blank except for text that reads “ENTER” and there is music, f-ing music playing. Wake up! it’s not 1990, it’s not acceptable to put auto-starting music on a website. If you are brave enough to click “ENTER” you greeted with a website that looks like it was made by one armed monkey on an acid trip; seriously my left nut could design a better website.
Oh, and the kicker is the contact info they provide – Anytown Cares 1234 N. Elm Street Anytown, Anystate 12345 (123) 123-4567 info@anytowncares.coolexample.com
Seriously dude if you bought anything from these people, you sir are a fucking idiot.Actually, the jury came back, you are a fucking idiot.I’m done with you, one more comment with an irrelevant link and you will be permanently banned.Jury came back on this one too, your banned.Hahah, looking for an app that records phone conversation and found this, but love your last post about that Id10T, no likey those sort of pipl! THEY DON”T LEARN!!
btw, nice piece of invention…
@Mark Guadalupe
Yep, I’m not sure… I guess he thought I was an idiot and would not notice he left a spamy comment again.
Thanks for your kind words.
So ummm… Back to the topic. How about Bluetooth?
@Paulnicholson
I’m sure that it’s possible to rig a setup with bluetooth but it’s beyond what I wanted to get into. In this case wires don’t bother me.
Bluetooth? Hmmmm. Sounds like a possible job for an arduino board and a Bluetooth shield. I’ve been doing some arduino work lately ( http://www.arduino.cc — open source hardware platform ) and while it may be hardware overkill for such a thing, it also opens you up to all sorts of other hardware fun. Check it out. They also have a wave shield available, but I don’t think you can record sound with it. More likely you would just want to go through USB port back to computer with sound files. The reason I searched for recordable iPhone calls is that I often have to do technical interviews with recruiters (like for java programming jobs), and I wanted a way to record the phone calls so I can go back and study all the suject matter around questions I was unable to answer.
I enjoyed reading your blog. I just read that Brits vote iPhone 8th greatest invention. I love my Iphone.
On my Symbian phone I simply run a call recorder app in the background. Too bad that the p.o.s. iPhone can’t do it.
@Sebhelyesfarku
Calling the iPhone a POS because it lacks what is arguably a minor feature (in terms of the number of people asking for it) is a bit… silly.
How many iPhones have sold? I’d like a piece of that POS pie.
I’d gladly buy a device that offered this function even at $100 to $250.
You say this device only outputs mono to the recording device (as I can see from the schematic), I was just wondering, how easy/difficult would it be to have a stereo output where I can record me on one channel and the “victim” on the other?
A use I could see for that is, if both people are talking at the same time (which occurs often), one of the channels can be turned down so you can recover what the other said.
@Dave M
Recording your side and the other persons side of the conversation using one channel for each does not work. The problem is that most of your small digital recorders only record in mono, so you could separate the sides of the conversation to each channel but (depending on the device your using) that audio is going to get combined anyway and cause the other person to hear themselves in their ear piece.
If you had a recording device that kept the channels separate then it would probably work. I was trying to come up with a device that was as universal as possible.