Antique Phone Doorbell


[Bryan] sent in this cool doorbell he made out of an antique phone. After seeing similar phones for $150 to $399, he picked one up on ebay for $10. After some cleaning and polishing, it was looking fantastic, but fairly useless. At this point, he broke it open and started hacking to turn it into a wireless doorbell. He picked up a cheap wireless doorbell and proceeded to gut it. The transmitter side got an aesthetic overhaul, a big fancy button and nice LED in a 50’s style  were added. The receiver side got hacked up as well. It was incapable of pushing the required voltage to ring the phone’s bell, so he had to do some searching for a better circuit. Since his knowledge of electronics was limited, he was looking for something that could be plugged in and work without much modification. Eventually, he found the Silvercom AG1170-s5. At $7, he swiped it up quick. It may be a bit of overkill, but he’s using an arduino to trigger the whole thing when it receives the signal. You can download the Arduino sketch on the site.

30 thoughts on “Antique Phone Doorbell

  1. If the ag1170-s5 doesn’t have enough juice to ring the bells, why doesn’t he just use the transmitter to open/close a physical or solid state relay (optioislator?) to ring the bell at a higher voltage from the power supply?

  2. I just use mine as a phone.

    Added a chip to convert pulse to DTMF (ripped out of an old cheap phone), and the offices PBX drives the ringer just dandy all by itself.

  3. The ag1170 has a pulse to tone conversion ability built-in already. He could just use it as a phone as well, and drive from a jack. An SSR would be the way to go for the doorbell though.

  4. Did anybody else notice he mouted a mechanical-ringer phone to the shelf holding his turntable? I know the vibration induced in the table would be quite small, but did it make anyone else chuckle just a little bit?


    Oh well.

  5. Phone ringers, especially the old mechanical kind, are nominally 90VRMS at 20 hertz (mine rang fine at 30VRMS, but YMMV). You don’t need a lot of current, though. Somewhere around I have a box with an AVR, some transistors, a transformer, current limit resistor, and a switch for US/brit/french ring patterns. I used 12V wall wart, but would probably work off a 9V battery. You could do the same with a few 555s, but an AVRtiny is cheaper nowadays…

    The AG1170 looks cheaper than the above circuit if I didn’t have all the above in my junk box…

  6. “Yeah, an optoisolator or relay would be a lot simpler. Why use an arduino to throw a simple switch? Simpler = cheaper, more reliable.”

    Because hackaday has turned into the “20 cool projects you can build with your arduino” and if they don’t mention it three times a day they lose money.

  7. “Because hackaday has turned into the “20 cool projects you can build with your arduino””

    at some point i’m expecting an arduino bot, where the entire physical structure of the robot is comprised of arduino boards held together by arduino controlled servos. and the post on hackaday will start off with the words “it may seem like a bit of overkill, but…”

  8. arduinos do recently seem to have become sort of a crutch for people who don’t want to bother with putting too much actual thought into designs.

    useful, but certainly overused.

  9. I like basic concept a lot. However, the specific implementation really is overkill.

    Someone suggested using the doorbell receiver to fire a relay, and use the relay to control a larger power supply to drive the bells. This makes more sense than the author’s design, but is not without complications. Ringer voltages run around 80 volts at 20 hertz. You probably aren’t going to find a power supply like that just lying around.

    i think I have a far easier solution: start with a small DC motor, ripped out of a toy or from the tray-eject mechanism of a CDROM drive. Using a few pieces of hobby brass and an RC airplane bushing, fashion a small crank, and attach the crank to the motor shaft. Remove the phone’s ringer coils, and install the motor so that the spinning crank can be linked to the armature with a music-wire pushrod or a small spring. The rotary motion of the motor is converted to reciprocating motion to drive the armature back and forth, thereby ringing the bells.

    an even better way is to eliminate the armature and clapper as well. Mount the motor so that the crank spins in between the bells. The crank arm should short enough that it just misses the bells as it rotates. Then, on the crank’s “handle,” you install a washer. The hole in the washer should be significantly larger than the diameter of the crank handle, so that it can move or “rattle” about. As the crank spins, centrifugal force drives the washer to the greatest radius. The washer will eventually strike one of the bells, and skip off. Because the washer is loose on the crank handle, it yields, allowing the crank to continue rotating. This is far easier to actually do than to explain in a text box.

    Interfacing a small DC motor to the door bell receiver would probably require nothing more than a single transistor and a resistor or two. No AC, no high voltages necessary. this mod is non-destructive. If you keep the parts you removed from the phone in a plastic bag, you can always restore the phone to original condition later, if you want to.

  10. using the ardiuino in place of say … designing the circuit from the ground up seems to me like the smartest way to “get it done” if you don’t plan to get an electronics degree.

    some nerds here seem aggressively elitist.

    i think it’s beautiful, stylish, functional and most importantly, it’s a project that has been completed.

  11. @dilweed

    I agree. Just because you could do the job in assembler, doesn’t mean one should turn up one’s nose at someone who does it in PROLOG. Personally, I think the whole point of a hack isn’t minimalism (that’s professional engineering), but Rube Goldbergesque overkill. I think for my next little project I’ll build a linear accelerator to throw a metal ball into a chute with enough velocity to power a small generator that powers up an ardiuinio to turn on an LED.

    Now that’s art…

  12. Snide said:
    “I agree. Just because you could do the job in assembler, doesn’t mean one should turn up one’s nose at someone who does it in PROLOG. Personally, I think the whole point of a hack isn’t minimalism (that’s professional engineering), but Rube Goldbergesque overkill. I think for my next little project I’ll build a linear accelerator to throw a metal ball into a chute with enough velocity to power a small generator that powers up an ardiuinio to turn on an LED.”

    Alright, make that LED a matrix that says “Arduino powered” and I’ll sign up.

  13. Hack-a-day is suffering from the same disease that killed MAKE magazine. The first symptom is arduino whoring. The second is steampunking. The last is superfluous shit that never serves a purpose, form or function.

  14. Hey everyone, Bryan (the author) here. Now that things have calmed down a little, here’s my two bits.

    A mechanical ringer is a good idea, one I also considered and mentioned in the project page. I went the more complicated route because I wanted to try something new. As far as making changes to the phone that are easily reversible, all I have to do with mine is unplug the external electronics box it’s connected to, plug it into a standard phone outlet, and I’m ready to use it as a normal phone.

    @josh malone
    I agree, a hardcore audiophile would slap my wrist for mounting a vibrating device next to a turntable. Luckily for me my doorbell doesn’t ring very often, and when it does my turntable isn’t usually on. Even if the phone was mounted elsewhere it would still interfere with the sound from the stereo, except it would be from the sound of the ringer and not the vibration shaking the needle on the vinyl.

    @everyone with a positive comment
    Thank you, I’m glad you liked my project. I really do appreciate it.

    @everyone who feels Arduinos are overplayed and are whoring up Make and Hack a Day, or that they’re for just for n00bs, or that the project is useless:

    Sure Arduinos are overplayed, much like anything else that becomes popular. They’re popular for a reason. If they were useless junk no one would use them. Arduinos are aimed at people who are just starting out with microcontrollers and electronics, or those who don’t care to get into details and just want to be able to create. Let’s not forget that all of us started out at as newbies in every subject we know, and it doesn’t make sense to make fun of those who are lower on the totem pole than us. Also, there will always be someone higher than us on the totem pole, no matter how much we know.

    I agree the project is useless, but it was a fun learning experience and a nerdy creative outlet. Maybe it will inspire someone else or help them with one of their projects, maybe it won’t. Who cares? I’m going to go drink a beer and enjoy life.

  15. if a person doesn’t have an engineering degree, they shouldn’t bother with hacking. also hackaday should only post projects that are within the grasp of hardcore hackers, and should not make an attempt to appeal to a broader audience….. stupid trolls.

    nice project bryan. keep learning and keep having fun. also the beer thing is good.

  16. At the risk of being repetitive, I’m going to call arduino abuse again. I just don’t see why it’s necessary to use a microcontroller to simulate a switch or a relay. It isn’t even the easy or lazy way out, it’s just the mentality of ‘might as well throw it in, since its here’.

    I think I could probably root around in the scrap box a bit and come up with something electromechanical that would work. Actually a lot of the parts needed are already part of the phone, so if you’ve got another to scrap. I’m assuming that the beauty of this is that the phone actually uses the original ringer and produces the original sound, so you aren’t wanting to just rebuild the ringer for low voltage. As has been mentioned before, the ringer signal from the phone line is low frequency AC. I seem to recall something about it being rated as 45 volts at 20 or 30 hertz, and the ringer coils are incredibly fine wire with thousands and thousands of turns, so they don’t draw a lot of juice. So I take an old low voltage relay, say 12 volts or so, with a pair of DPDT contacts, and wire the first set of contacts to act as a buzzer. This one goes to your fancy steampunkified brass doorbell button. Rivet a lump of lead to the relay’s contact arm to drop the frequency to a low buzz. Exact rate isn’t too important, just something lower than your typical AC hum. Wire the second set of contacts to chop the 12 volt DC into 12 volt AC and feed that into a transformer to step it up. One of the step down ones used to run doorbell buzzers should work. They’re 10 to 1, so wire it in reverse to step your chopped 12 volts up to 120 (or so. It’s not going to be very efficient at the low frequency and with your home made square wave AC) A few details like a capacitor across the contacts so they don’t arc, and another across the output to smooth things up a bit, and feed it into the ringer. Run the whole thing off of some dry cells, or the DC power source of your choice.


  17. @khordas
    i agree that there are plenty of simpler non-arduino ways to get this going, but like i mentioned in the article i don’t have a ton of electronics knowledge and liked the original ringer’s sound. based on simplicity, compare your above lengthy two paragraphs with “connect arduino to board designed to ring a phone, upload small amount of code, done.” yours is definitely clever though if it does work. someone else mentioned above that a relay wouldn’t cycle at 20hz, and if you’re going the mechanical route you could just use a small motor to ring the bells. who knows, maybe there are relays that can cycle that fast, i’m no expert.
    as for button style, i was going for more of a 1950’s look than steampunk, hence the hammertone paint and old stereo equipment parts. i can see the resemblance to steampunk though, had i gone with brass parts.

  18. Very interesting project. I have a BT GPO 746 phone as the main house phone (others are cordless) simply because of; retro value, the ringer can be heard in the garden it’s that loud.
    My cordless doorbell on the other hand,has multiple door chimes but cannot be heard clearly from every part of the house, and not at all outside. If there was a way to have the GPO phone ring (by itself) when the doorbell went AND still function as a normal house phone then even better.
    Im in the UK, we use 4 wires for the phones, although only 2 are used these days. One of the UNUSED ones is the RING wire. since I have the ring wire disconnected from every socket, could I use this wire to locally ring the phone? (taking it’s power from the phone socket/the wireless door chime)

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