Need help turning old payphone into dial-an-mp3 display - Page 1
Forum section: electronics / beginners

author: Funvoyager
author_rank: Contributor
timestamp: September 01, 2017, 03:43:42 am
content: Hi allI hope I'm posting in the right group.I'm a therapist and want to put an old payphone in my waiting room that "plays" mp3 files through the handset activated either by lifting receiver and or pressing the dialpad numbers.This is an art project mostly. I'd like patients in waiting room to lift receiver and hear positive affirmations, stories, comedy routines, etc.I bought a payphone off ebay and I figure id use something like an iPod to store audio files on "shuffle" mode activated somehow to play to each track. Not sure if I should have a mechanical or electronic solution. When people lift receiver and listen, it should play a random audio until hanging up or perhaps press any digit to shuffle through random sound files.This should be low tech or reasonably doable for a non electronics person (me) to do.anyone who can offer advice would be appreciated!!!Thanks??

author: sled
author_rank: Contributor
timestamp: September 01, 2017, 01:54:38 pm
content: Hey there,most audio players like the iPod have a multi-function headphone jack that allows play/pause, track control and volume to be adjusted. I'd take one of these "headset remote controls" apart and solder extension wires to the buttons on the payphone. However basic electronics and soldering skills are needed, maybe check for a local hacker/makerspace close by that can help you.

author: Funvoyager
author_rank: Contributor
timestamp: September 01, 2017, 02:30:26 pm
content: Wow that's a great idea!That opens up the possibility of buttons being dedicated to certain functions like "for list of local support groups, press one, techniques on mindfulness, suicide prevention, etc., Press two, humor/positive messages, press three, lectures or podcasts, four..." And so onIf I can figure this out I'll post pics of it in the projects section in case anyone is interested.If this is beyond my scope and I have to hire someone to do this, if you or anyone reading this knows where to advertise for unusual jobs like this, please let me know.I'm in falls church Virginia.Thanks for those great tips!CheersJohn

author: skarecrow
author_rank: Regular Contributor
timestamp: September 01, 2017, 05:00:04 pm
content: Was it telco owned phone (Verizon, Bell South, Nynex, etc.) or a COCOT (customer owned coin operated telephone)? That could make a difference in how you should go about achieving your goal.I've always loved payphones and used to own a COCOT myself until an ex-roommate screwed me over after begging me to let him borrow it. I would LOVE to see the progress of this project.One idea for you... assuming you can get inside the phone, there should be plenty of room to fit a small DTMF decoder and a Raspberry pi. Have the pi control the functions and playlist. This should be MUCH easier than trying to control it by splicing in one of those button remote things, and it'll keep the true feeling of using the phone. The person would still hear the normal sounds of the buttons. This way your only limits are your imagination. You could even have games on it, let your patients check in or create new appointments, the list goes on. You could even have it do things if someone inserts a coin, as most pay phones send a tone (or series of 2 or 5 tones for dime and quarter) over the line to signal the telco what coin was inserted.Sent from my XT1565 using Tapatalk

author: Funvoyager
author_rank: Contributor
timestamp: September 01, 2017, 05:19:08 pm
content: Hey - thanks for those great ideas! I love preserving the "feel" of the payphone's tones and the ding from depositing coins. Good idea about the coin sounds. Probably doesn't have a key though so I'd have to figure out how to return the coin or I could donate the coins to a local charity that appeals to my client base.Shipping costs on this payphone were $66. It's pretty heavy - more so than I expected. I'll be unpacking it this afternoon so, hopefully, I'll be able to answer your question about which type or company this payphone came from.I'll post pics here and if I can figure out how to open the actual phone up, I'll post pics of the guts and subsequent upgrades with some of the suggestions you all are providing. Now that I think about it, I'll probably have to find some special tools but I don't want to get ahead of myself.More later...

author: skarecrow
author_rank: Regular Contributor
timestamp: September 01, 2017, 05:31:38 pm
content: I'm actually having dinner in NYC this evening with several friends who are huge payphone lovers. I'm sure many of them would love to see the progress as well, and could possibly offer help and maybe even be able to get a key for you. I'll try to get some of them to check out the forum.Sent from my XT1565 using Tapatalk

author: Funvoyager
author_rank: Contributor
timestamp: September 01, 2017, 06:35:35 pm
content: That's cool!I did try to post a reply with some pics a minute ago but it's not here so I may have to post one pic at a time.This is a heavy duty phone - made the mistake of not unpacking it outside because a bunch of fine iron shavings and grime ringed the carpet! Also it smells like the ashtray in the teacher's lounge circa 1960s - had to leave it on the porch to air out.One of the pics shows it's owned and operated by Teletrust, Inc (Sherman, TX).Coin box lid comes off and there is no key - the side has a utility key hole for opening the back as you probably already know. So, I'm going to have to track down a key or figure out how to break into it without ruining the old look of this phone.I'll send pics in a subsequent post so they'll hopefully get posted.Thanks!J

author: skarecrow
author_rank: Regular Contributor
timestamp: September 01, 2017, 07:48:34 pm
content: Quote from: Funvoyager on September 01, 2017, 06:35:35 pmArgh! You just reminded me I have one of those keys in my work truck that I was supposed to bring with me. They can be had on eBay for less than $5 each. I believe I paid $7 shipped for 2 of them.Sent from my XT1565 using Tapatalk

author: ez24
author_rank: Super Contributor
timestamp: September 01, 2017, 08:17:38 pm
content: Quote from: Funvoyager on September 01, 2017, 02:30:26 pmIf you do be sure to put a link to it.I bet you can find some good sound clips from here:https://archive.org/details/oldtimeradio?sort=titleSorterI used some for a video once. Try the creaking door from CBS :https://archive.org/details/CbsRadioMysteryTheater1977-1978_566I also used some from Whistler:https://archive.org/details/Whistler-1945_690Some sound clips from these old shows may increase your businessOr maybe once you figure this out, you can sell these since it is a good ideaI imagine you could customize the clips and have the patient enter a code to hear their message ( like "pay your bill")I would try bluetooth to load the clips.Sounds like a fun project.

author: Funvoyager
author_rank: Contributor
timestamp: September 02, 2017, 02:03:19 am
content: Hey that's great to know I can get a key on eBay. Is the side lock the same as the coin box?Those are cool links ez thank u for that. I'll bet there's a ton of audio files, old radio shiwd, sound effects. Pay your Bill - lol - I like that one!This project reminds me of the kiosks that they did with computers and a dial-up modems 25+ years ago but way older school.I showed a pic of the phone to one of my 12 yo clients who, of, course, never saw this before. It was a real hit. I'll bet half my young clients know how to use raspberry pi and wire things - it'll be cool to show them as piece of this old school technologyI'm not able to attach pics so I'll load them up on the cloud and add links ...

author: Brumby
author_rank: Unknown
timestamp: September 02, 2017, 02:06:29 am
content: You should be able to upload images here - just be aware that there are size limitations.If you do try and it fails, there should be a message somewhere on the screen that will tell you why.

author: Funvoyager
author_rank: Contributor
timestamp: September 02, 2017, 02:36:04 am
content: Ok thanks

author: skarecrow
author_rank: Regular Contributor
timestamp: September 02, 2017, 11:22:48 pm
content: Quote from: Funvoyager on September 02, 2017, 02:03:19 amWell the "key" I got on eBay is more of a tool than a key. It's not gonna get you into the actual locks. I've seen inside a few payphones, but sadly haven't actually opened any myself. Not even my own that I used to have. I did see someone pick one of the locks on a pay phone once. There was a whole bunch of phones and probably a few hundred people with lockpicks working on the for the whole weekend.I just sent a link to this post to a friend of mine with much more knowledge about phones and locks than myself. Hopefully he'll pay us a visit.Sent from my XT1565 using Tapatalk

author: Beamin
author_rank: Super Contributor
timestamp: September 02, 2017, 11:44:08 pm
content: I honestly think this might be a bit too hard as a first timer. I have been playing with electronics for a few years and think that would be a challenging project. The raspberry pi idea (or Arduino which is like a micro controller which takes inputs signals then makes output signals you control using computer code called "c programing") would be best but you will have to:Learn:python- programming codeLinux- operating system that's like ms dos but also has a Mac like interfacesolderingVoltmeterfiguring out what components like resistors and transistors dohow current and electricity flowALOT of time messing about with some mechanical tinkeringTrying to get things working together only to realize they are not like lego blocks: different voltages- have to build power supplies and getting the payphone output down to "logic level 5 volts" so the raspberry pi can understand it with a "DTMF" which is the beeps the numbers make turned into signals the pi which is going to be the mp3 player understandsGetting the pi's output to play over the head set so impedance and voltage matching.If you do get it working I think you will be a future electronics hobbyist. Expect to spend ALOT of time on this and trying a lot of things that won't work as you blow things up by accident. Not trying to discourage you but rather setting realistic expectations.Best thing would be to pair up with someone who has built electronics projects before. Its easy to get stuck on things and get frustrated. Look up "Ben Heck" or "Mikes electric stuff" on youtube to see how much knowledge equipment and time it takes to do "simple things" like make an ipod screen or a controller work in your project.This forum is really helpful but expect them to give really technical answers that require a lot of reading up to understand.

author: Funvoyager
author_rank: Contributor
timestamp: September 03, 2017, 12:05:04 am
content: Thank you for your honest and thorough description and advice.You are right, This is WAY over my head. I just looked on upwork.com and I've used that and similar sites to hire people in the past. I also posited an ad on CL volunteer section for someone with these skills. I'm going to tap into the other networks you mentioned and local schools/universities and any other suggestions you all haveMy clients are gifted teens with autism spectrum and gender incongruence conditions and this type of project is something they can probably do or learn. Some of them do programming, robotics, etc., So I feel confident that if I supply the parts and link up with a local expert, that they will succeed or have fun trying.I'll post updates here and this can be a user's manual for them as we run into challenges.I've coordinated these kinds of things in the past and it's amazing how creative and inventive people can be surrounding an unusual or challenging project.I'll keep y'all posted!Btw I'm in northern Virginia so if anyone is local and wants to contact me or drop by when we kick this project off, please let me know!

author: Beamin
author_rank: Super Contributor
timestamp: September 03, 2017, 12:14:01 am
content: Quote from: Funvoyager on September 03, 2017, 12:05:04 amI think some of the people on this forum have autism or asbergersBe sure to post lots of pictures I'm really excited to see how this comes out. Since it will have to be built in moduals maybe you can mail off bit to people on this forum and have them work on each bit: one person builds a power supply another a DTMF converter someone wires the raspberry pi someone else writes the code etc. That way you can get experts on here and you won't have to pay random people that don't know what they are doing.

author: skarecrow
author_rank: Regular Contributor
timestamp: September 03, 2017, 01:21:58 pm
content: I don't see much difficulty at all with making this happen. All you need to do is supply power to the phone and the raspberry pi, tap into the audio right from the handset wires, and have the software on the pi handle everything. The electronics part shouldn't take more than a few minutes to complete.The software side might be a little more difficult, but still not that hard. Makes me want to get another pay phone and do it myself. I don't think there's any software out there written specifically for what you're trying to do. Basically what you need is a pbx server that you don't actually dial into, because you're in as soon as you pick up the handset. You could trick it into thinking a call came in by triggering it when the handset is lifted and the pbx handles the rest. The pbx software will handle the dtmf decoding and move the user through all the menus that you create. Most will support music on hold, which you could use for playing back the mp3's, but I don't know of any that will let the user control a playlist. I do think this would be a good starting off point for you though. It may be possible to pass off control to another program that'll handle playlist control. But that's all a software thing, nothing electronic or mechanical about it.Someone else mentioned using bluetooth to control the playlist. Please explain how (and more importantly WHY) that should be considered. I've been trying to think of any reason to use bluetooth at all and I'm coming up blank.Sent from my XT1565 using Tapatalk

author: Beamin
author_rank: Super Contributor
timestamp: September 03, 2017, 05:10:11 pm
content: Quote from: skarecrow on September 03, 2017, 01:21:58 pmA few minutes?The phones not going to be at logic level voltages. Also how is a new user supposed to know how to operate or what a pbx system is? The I/o pins can't just take tones into them as far as I know so what interface on the pi would you use? Learning to solder or taking the phone apart and learning how to use a multimeter all in a few minutes and learning the pi plus creating the SDcard and learning pbx software and learning a programming language to write new software that controls an mp3 player? I guess we have different definitions of "a few". When you say things like this to a "newbie" and they realize its not that simple it is really off putting. Doesn't the phone run off 60 volts? You are going to need to build a supply for the phone then build a converter so you don't blow up the pi then also modify/cut open a usb supply to run the pi, then get the handset to work both with the pi and the phone voltages. Either you are missing something or you are the fastest prototype builder in the world. If you do really have the skills to do this why not offer to have the parts shipped to you so you can help them? Setting up a pi for the first time takes more then a few minutes and also getting to programs to run on Linux isn't like windows plug and play.

author: Towger
author_rank: Super Contributor
timestamp: September 03, 2017, 06:06:39 pm
content: There is no need to connect to a PABX. The guts of the phone can be scrapped. The pi has stereo audio out, just a matter of connecting it up to a cheap 8ohm speaker in the handset etc.

author: skarecrow
author_rank: Regular Contributor
timestamp: September 03, 2017, 06:53:21 pm
content: Quote from: Beamin on September 03, 2017, 05:10:11 pmYes, just a few minutes for the electronics portion of the project. Using the pi to handle the software (I just used a pbx as an example of a system that's already 90% of what needs to be done) the only things left to be done is supply power, and tap into the audio at the handset wires. There's absolutely no need to get into any other electronics inside the phone or deal with logic to make it work with the pi in the suggested way. Yes, the pi can decode the dtmf tones (they have audio input and output built in, no need to use I/O pins) and send commands to the software to make it do the requested task.The handset is just a microphone and a speaker. That's the only part of the phone that really needs to be touched. The speaker part of it doesn't even need to be connected to the phone, as all of the audio will be coming from the audio output of the pi.I know I'm not covering every detail involved, but I'm not really missing much, if anything. I didn't nay the whole project would only take a few minutes, just the actual working with electronics part of it. The OP first needs to do some research on the power requirements of the phone before touching it. I'm sure there's thousands of much more complicated ways to achieve the same end result, but I believe mine requires the least amount of electronics experience, which I'm pretty sure was what the OP was looking for.The software is where the real time is going to be spent. Learning programming languages is most likely not necessary, but always useful, and will make things easier. It may be possible to use already existing programs together to get everything done. One program listens to the user input, analyzes it, and passes a result to another program to perform another function. There may actually already be a fully made software solution out there, I wouldn't be surprised, but it might not be free. Look at dial-in services that have existed for years like moviefone. Once you're connected you use the keypad to navigate the voice menus. I don't know what software they use (do they even exist anymore?).If you can find software like moviefone and simply supply correct power and splice into the audio you're pretty much done. Of course if you wanted to add other features (like triggering coin return if someone inserted money or making it ring) you would need to dig more into the electronics of the phone.Sent from my XT1565 using Tapatalk

author: skarecrow
author_rank: Regular Contributor
timestamp: September 03, 2017, 07:13:34 pm
content: Quote from: Towger on September 03, 2017, 06:06:39 pmThe guts CAN be scrapped, but everything is already there to have a working keypad, so it saves a lot of work by just keeping it there. I wasn't suggesting connecting the phone to an actual pbx through the wires, I was talking about the pi running a software solution with a menu system similar to the existing pbx software packages available. The software can turn the dtmf tones it receives through the pi's audio input and navigate the system, just as if you had dialed into a real pbx.Are handset speakers 8ohm? For some reason I thought they were 32.Sent from my XT1565 using Tapatalk

author: ez24
author_rank: Super Contributor
timestamp: September 03, 2017, 11:28:19 pm
content: Quote from: skarecrow on September 03, 2017, 01:21:58 pmThe owner of the phone could customize what happens when someone uses the phone. Custom messages or clips could be played for different people. A doctor could give a message to their client before they see them.

author: ez24
author_rank: Super Contributor
timestamp: September 03, 2017, 11:31:03 pm
content: I suggest the OP start a Kickstarter on this. He could request help on this forum to start it. I like this one.

author: skarecrow
author_rank: Regular Contributor
timestamp: September 04, 2017, 11:32:01 am
content: Quote from: ez24 on September 03, 2017, 11:28:19 pmBut that's already the reason for using the existing key pad. What would be the point of adding bluetooth? I see no reason to use it. The OP also stated they liked the idea of keeping the natural feel of the phone which pretty much rules out doing anything that I can imagine with bluetooth.Also the OP is a self proclaimed 'non electronics person'. Suggesting the use of bluetooth adds a lot of complexity to a very easy solution.Sent from my XT1565 using Tapatalk

author: Beamin
author_rank: Super Contributor
timestamp: September 04, 2017, 12:50:37 pm
content: Quote from: skarecrow on September 03, 2017, 07:13:34 pmYou realize the key pad doesn't put out the tones right?Also the key pad is hooked up in a matrix where pressing a button doesn't just switch on a wire it makes combinations which have to be sorted out. I don't know where the pi would have separate audio out and audio in jacks that you could just plug into. It has one jack that's shared with something else like composite video. Accessing this might require a program through python. I found personally it was much easier to use the Arduino and C compiler to do things then the pi. Plus I think C is more useful if you are going to spend your effort and time.I have a feeling you are at that stage in the hobby where you have learned a little and everything seems doable and easy. The next phase is finding out that things are much more complex then you thought and you realize that you have to focus on one area to excel at because there are only so many hours in a day and to figure out everything would take more then a four year degree. I had a guy working for me that was like this. The result was all kinds of stuff taken apart not put back together and a whole bunch of never to be finished projects. He would be super enthusiastic at first but then he would get to a hurdle and say fuck it this shits not going to work and give up.

author: skarecrow
author_rank: Regular Contributor
timestamp: September 04, 2017, 02:16:17 pm
content: Quote from: Beamin on September 04, 2017, 12:50:37 pmThat's the exact reason I recommended NOT scrapping the guts of the phone. The keypad only works because of the rest of the "guts" of the phone. The end result is a pair of audio tones that can be fed into the pi through audio. I thought they had an audio input, but if they don't you can use a usb sound card plugged into one of the empty usb slots to solve that problem.Sent from my XT1565 using Tapatalk

author: station240
author_rank: Unknown
timestamp: September 04, 2017, 05:08:34 pm
content: Should simply be a case of powering the phone and getting signals in and out of the line.power in.dial tones out.voice signals in (music)Not sure if this payphone uses DTMF (google it) signals, or some form of digital.Certainly possible to make all this work without having to open up the phone. Thought it may still need that done to clean it.

author: Towger
author_rank: Super Contributor
timestamp: September 04, 2017, 08:47:01 pm
content: Quote from: skarecrow on September 03, 2017, 07:13:34 pmOff the top of my head I think old phone hansets might be 600ohms.

author: Beamin
author_rank: Super Contributor
timestamp: September 05, 2017, 08:38:00 pm
content: Quote from: skarecrow on September 03, 2017, 07:13:34 pm

author: Funvoyager
author_rank: Contributor
timestamp: September 05, 2017, 11:24:30 pm
content: Hi everybody. OP here.I appreciate all the interest and debate on the fine details of this project. It looks like there are a number of ways this could be done and that I'll need to hire a pro to oversee this project, recommend the final list of supplies, etc., and triage the various simple to complex solutions based on budget and level of interest and ability with the groupRegarding the kickstarter idea, that's a really good suggestion or maybe gofundme ?? I could describe the project without getting too technical but mention the requirements to demonstrate the scope of complexity and need for help.If it's not funded at the highest level then maybe a low tech backup plan could be employed.I'm hopeful because even though I'm not knowledgeable of the different technical solutions being discussed, I'm confident that, at a minimum, I could make the phone play a random or continuous play audio of something that is activated by lifting the receiver - or maybe it constantly is on and plays to the ear piece and I could try to recruit people interested in the potential to upgrade it to how ever fancy and cool it actually could beProblems I'm working on now are purely mechanical in the meantime:1) finding a key to open phone or using a hacksaw blade ?? To saw through lock. This thing is a tank.2) getting a piece of plywood to attach to drywall to hang phone. It's way heavier than I imagined and want to make sure it's secure to the wall. I can't just use molly bolts, I'm going to have to distribute the load to support this phone.3) figure out how to unscrew handset mouth and earpiece. It's either tight or glued or something. That way I can have access to handset insides in case I end up going low tech and put an actual mp3 player or speaker inside the handset that is connected to a charge cable threaded through the tube into phone, then drill hole through case and thread charge cable to an inconspicuous outlet so out stays on 24/7I'm pretty excited at the low to high tech solutions to this. Money doesn't seem to be a big barrier unless the parts are really expensive. I'm thinking that the money is needed for labor for each level of expertise in consulting and oversightI've searched for clubs and makerspace ?? places in the DC area and am surprised there isn't a club or group that is already in place. Maybe dc is less technical compared to other places or I'm not advertising in the right circles. I miss the days when radio shack was more prevalentI'm going to get some bids from upwork to estimate labor costs. My guess is that it's a pretty specialized job bc it incorporates new and technology and programming like raspberry pi and also an understanding of obsolete technology and old school electronics. I imagine that is an elite group that has that full range of expertiseI'll keep you all posted.Thanks for the ideas and encouragement!John

author: ez24
author_rank: Super Contributor
timestamp: September 06, 2017, 12:12:40 am
content: QuoteMaybe some ways to not open the phone.Use LADAR and AI to externally determine what buttons are pressed. Come up with a technology that allows you to transmit sound through the air but only be able to hear it at a predetermined spot (handset).A less high level - use a cut-off wheel on a grinder and carefully open the back and rip out the guts. No matter what you do, do not mar the outside.

author: skarecrow
author_rank: Regular Contributor
timestamp: September 06, 2017, 01:42:50 am
content: Quote from: Beamin on September 05, 2017, 08:38:00 pm

author: Funvoyager
author_rank: Contributor
timestamp: September 06, 2017, 02:38:23 am
content: I posted a reply that ended up in an earlier post.Anyway, the idea of shipping projects out... I'm wondering, are there any Skype or netmeeting video clubs/discussions that anyone would want to do? Since there are few people who do Egypt you all for it might be fun and prescribing schedule virtual build and problem solving sessionsJohn

author: Beamin
author_rank: Super Contributor
timestamp: September 06, 2017, 04:25:38 am
content: Quote from: Funvoyager on September 06, 2017, 02:38:23 amI think kick starter and go fund me want to see a return on investment. Maybe that's just kickstarter. Better to get a person going with a concreate plan and design before you start asking for money as you won't know how much to spend until you do. Maybe find a local electronics repair shop that has good google reviews. Many of those people like to tinker or try putting up ads at local community colleges. This is going to be a challenge. I know how much I would charge to build this and it wouldn't be cheap and take about a month to get the final product. I wish I still had my garage I would offer to work on some of it but some tools are going to be needed as little things always pop up like trying to get open the handset which maybe sealed..

author: ez24
author_rank: Super Contributor
timestamp: September 06, 2017, 04:37:33 am
content: Quote from: Beamin on September 06, 2017, 04:25:38 amIf you can hire 200 PhDs like Google (for health apps for their watch) , use the handset for health diagnostics. Like BP. If you go KS say it will detect cancer (there is a lot of BS there). Use it to determine the health of your patients. Seems like a good product for a doctors office. Patients would have fun with it.

author: Beamin
author_rank: Super Contributor
timestamp: September 06, 2017, 04:41:14 am
content: Quote from: ez24 on September 06, 2017, 04:37:33 amThe Kick starter site measures brain activity. The higher the water seere gets in dollars the lower the brain activity of the donors.

author: rstofer
author_rank: Super Contributor
timestamp: September 06, 2017, 04:52:22 am
content: It seems to me that the requirement for 48 VDC is driven by the DTMF encoder in the keypad. So, scrap it!In the end, the keypad will probably use 7 wires, 4 for rows and 3 for columns and the usual scan by rows/columns will work with any micro at any voltage level. Let the microcontroller create some kind of button-pressed tone. There are a lot of keypad applications that do this kind of thing. There is no reason the user has to hear DTMF although, if it is really a requirement, it could probably be created by the microcontroller. This would be an advanced feature. Just send a single consistent tone - that's the easy way.Don't forget, the dial tone, if it is going to be created, stops after the first digit.If the tones are going to be used, they can be prerecorded on the audio output gadget, whatever it is. The uC can select which tone (or presentation) is to be played at any given time.http://www.nerdkits.com/forum/thread/1885/

author: Funvoyager
author_rank: Contributor
timestamp: September 06, 2017, 01:37:00 pm
content: Regarding the value of this, it might be tough marketing I it as a device for medical procedures (NO if so understand your suggestion cirrectkt( - the educational and marketing angle is what is probably do if this was built and duplicated because it could cut down on boredom in the waiting room while also having a combination of entertainment and education.I'm thinking self helo, health tios, answers to questions people don't wardrobes doctor (STD risks, testing, prevention, rtc), and I wonder now if this could be a two way communication device. For instance, looking - press one for durveys, then press one for yes, 2for no... And a confidential voice mail "suggestion box" etc

author: Beamin
author_rank: Super Contributor
timestamp: September 06, 2017, 04:09:07 pm
content: Quote from: skarecrowQuote from: skarecrowBy the way I tried this it makes some noise but its way too quiet to actually hear what it is. You can just tell that its connected but even putting your ear right up to it doesn't make an intelligible sound. You will need a simple amplifier circuit and a little output transformer.

author: skarecrow
author_rank: Regular Contributor
timestamp: September 06, 2017, 07:21:10 pm
content: Quote from: Beamin on September 06, 2017, 04:09:07 pmThat quote belongs to someone else. I assumed they just meant the speaker that's already in the handset, which is why I questioned if they were 8ohm because I couldn't remember.Could you give some more details on exactly what you tried and with what equipment? Do you have a payphone also? The speaker output of a sound card should be more than powerful enough to drive a handset speaker. I've done it many times myself (with regular house phones though, not with a pay phone.). Back in high school I turned my 386 computer into a speaker phone by cutting a phone handset cord and putting some connectors on the wire to plug it into my sound card.Sent from my XT1565 using Tapatalk

author: Funvoyager
author_rank: Contributor
timestamp: September 11, 2017, 02:10:29 am
content: Update...Ok I think the reality of the electronics expertise and shortage of local resources is sinking in nSo. What I'd like to try on my own for "version 1.0" is a mostly mechanical fix. Here is my plan. ..Open handset and take out everything inside. If I can't break into actual case of body then I cut the metal "cord" where it comes out of the phone case. Pull out wires.Then put a headphone speaker in the ear piece and run the power wire down through the cable. Then insert the cut end of the cable with wire back through the hole in the case. Use a molly bolt type gizmo on the end of the cable so phone cable can't get pulled back out.Prior to this i could drill an exit hole in bottom of phone case so when I reinsert cable i can feed power line in and then back out bottom of phone case where I can discretely feed it to a hidden mp3 player a few feet away.I can then add and remove songs manually and simply hit "play" dial down the volume so hopefully it can only be heard when receiver is out next to eat.Version 2 can may be he inspired by the experience of using version 1 and inspire a future group of tech volunteer youths who come to my practice and immediately see how much better this could be by incorporating the great ideas shared here.One final question...I can't unscrew the earpiece and mouthpiece. Does it actually come unscrewed or is it glued so no one can tamper with it? Maybe I need to use a special tool to create the torque i need. I wanted to ask in case I could ruin it otherwise.I'll post pics or a link to pics when I get started.Thanks again everyone.

author: Beamin
author_rank: Super Contributor
timestamp: September 18, 2017, 09:34:12 pm
content: Quote from: Funvoyager on September 11, 2017, 02:10:29 amThere will be four wires in the cord to the handset thing. Two wires power the speaker and two power the microphone. You can take a digital multimeter to test which wires belong to which. This would be done by selecting the "ohms" setting and connecting the wires to the red and black leads. You will get a reading of 0 or some number when the proper two wires are connected. You can also use the "diode" setting which creates a beep sound on the meter when you have a connection. Touch the red and black wires on the meter together to see what sound and reading your meter makes. In theory the pair with the lower resistance (closer to 0 or 0) reading will be the speaker. You can also try to plug the wires into your MP3 player until sound comes out. I would imagine the head set doesn't come apart to keep people from connecting "black boxes/blue boxes" (etc- boxes) to get free phone calls back when you could do that. If sound doesn't come out the reason is dealing with "impedance" of the speaker not matching what the mp3/amplifier can put out. Sounds simple but may a bit tricky. Remember a mp3 player will have 3 wires not four for the two speakers. This is because they share a common "ground" or "negative" lead.

author: Beamin
author_rank: Super Contributor
timestamp: September 18, 2017, 09:36:44 pm
content: Quote from: skarecrow on September 06, 2017, 07:21:10 pmNo offence but it sounds like you are just starting out in this hobby so I don't really feel you can adequately answer any questions I have that I haven't already tried when I was younger. Maybe do some more reading or watching eevlog videos.

author: Beamin
author_rank: Super Contributor
timestamp: June 11, 2018, 12:56:38 pm
content: What ever became of this? I wonder if the OP actually got this working. Would be an interesting product but I imagine holding a phone to your ear would be tiresome. Would also be interesting to see how long it took them, if they gave up in frustration, or if they are now on their way to a BS in EE.What ever happened to all the worlds pay phones? I know the few that are left where I live have had the coins smashed out of them long ago or even had the whole thing removed for metal quite bold as there were located at busy bus stops and 100% chance someone would see you stealing it. A few months ago I was in the city a guy asked me "Do you know if there is still a 'coin phone' at the end of this street or where it went?" I explained in the 9 years I lived here I have never seen any payphones in this part of the city. I'm guessing he was jail for a very long time and didn't realize they give away free cell phones on every corner to low income people. A friend of mine got four of them when were walking around the city one day, probably could have got more if we tried. The phones were shit; one was three different colored sprint phones refurbished into a "new" one with a crooked paper sticker on it that said "budget mobile" covering the sprint logos. We tried calling customer service and it gave the options of using your credit card to buy minutes or customer service that didn't exist and would just play hold music non stop. I guess when you use all the minutes you just throw it away and go to the street corner and get another one. So wasteful and I bet these companies make a fortune off each one paid for by the $0.04 cent fee on our cell phone bills.