This Old Phone part 3: Ring my bell.

I have the Bluetooth solution and verified operation of the candlestick handset. What was missing was an old timey ringer. Back in a day, a wall mounted ringer assemble was usually installed next to the handset.  This would require a 90V AC to ring the bell.  I want to have an old style ringer but I didn’t want to hassle with the 90 Volt requirements.   I found a surplus bell from an old phone parts supplier.  I removed the larger coil and installed a 5 volt relay with tie-wraps and wire.  I made it work.

The ringing is from a 15 to 20 Hz pulse that duty cycles on for 2 seconds and off for a couple seconds.  I piecemealed this circuit to be triggered from the incoming signal from the speaker. It sets the first 555 for the on off duty cycle while the second 555 is for the 20Hz ringing.

In order to make this a desktop application and something that doesn’t have to be anchored to a wall, I decided to create a “ringer base” which will also act as a charging station.  I found a nice small black cigar box that will serve just right for the ringer base.  The candlestick phone will sit on top and when a call comes in, lifting it off the base will cause the ringer to stop and answer the call.

I created 3 small PCBs from proto material I had hanging around my lab.  The larger one holds the ringer and charger circuit assembly.  I have a single transistor amplifier to act as a simple Schmitt trigger on a smaller PCB ( similar circuit I used for the condenser microphone from last time).  In the center is my connector board which will interface to the phone, charging power, “answer” signal, and speaker from the receiver.

The lid of the cigar box slides out. I cut out an access point to this molex connector, again from my spare parts bin, where at one point I got this assortment of connectors.  I routed out the underside so that the connector can stick up enough to mate with the base of the phone.

So far all things are in place. Next time I will put it all together with the interconnections from the phone.

This old ( Bluetooth connected) phone Part 2:

Since the old carbon microphone was not operational anymore, I needed to up grade to a more modern approach for the BC127 module. I found an inexpensive electret condenser microphone. Working with these can be a little tricky and not quite straightforward depending on the gain of target application  and how much voltage you intend to run it off. Given that I am trying to run this all off of a 3 V source, I didn’t have enough amplification to directly drive the microphone into the input of the BC127.

This this little circuit came in handy:

I built the circuit on a solder-able  breadboard and tested it with an oscilloscope first.  I verified the circuit by  testing it on the prototype platform, currently resembling a mad scientist’s tangled mess of wires.

Success! A call made from my land-line to my cell phone paired to the purpletooth jamboree board connected to this kluge of wires, iron and alligator clips was rather exciting for a geek. I was able to test the microphone’s ability to pick up my voice from about 3 feet away before dropping off.

 

Next step: In part 3, I really want to ring an old time ringer which I purchased. This will requiring hacking into the code a little bit to set a GPIO active to engage the bell. The problem is that the bell will require a higher voltage too and may defeat my dream of being somewhat rechargeable and running off of a single battery and voltage source.  At the very least, I will test the connection to the switch which will engage the “answer” mechanism ( play button on the Jamboree board).

Halloween prop 2015

It was early September when a friend approached me about a Halloween costume project. “I heard you could augment a gun prop with LEDs!”  Intrigued, I encouraged her to elaborate more. She wanted to recreate the character, Rocket, from Guardians of the Galaxy to rest on her shoulder while she was dressed as something else.  Then she mentioned using a puppet for the raccoon and the project took a life of it’s own.

I had 6 short weeks to augment a Nerf Blaster with a sequence of LEDs, animate the head of a raccoon puppet, and make an industrial backpack to go along with the gun.  I drafted an overall plan for this attempt:

The Gun:

3 bright White LEDs ( 80mA each) for inside the barrel.

2 Purple LEDs for the tip of the muzzle

10 orange LED’s distributed to the chambers and butt of the stock.

The Backpack:

1  Blue Circular Bar-graph LED (with 16 LEDs)

1 tri-color LED

Racoon Puppet:

2 Red LED’s for the eyes

1 mini position servo 180 degrees for head movement

2 condenser microphones for the ears

I wanted a firing sequence that would start at the backpack with the tri-color LED cycling through it’s rainbow while the circular Bar graph started up. At about halfway around the circular bar-graph, a few of the orange LEDs will start to light up ( flames). At full circle, the bright white LED’s in the barrel would fire a sequence of 3 pulse with the purple LED’s as an effect on the muzzle. Then the rest of the Orange LED’s would all be lit ( after burn) while the Circular LED cycles down.

For the Raccoon, his eyes would stay lit. The intention was to have him noise activated. If the left ear picked up a noise  louder than the right ear, move head to the left. The same for the right and if the sound was loud ( a clap or shout) the firing sequence for the gun would start. That was the intent anyway. The problem was the sampling rate for the analog input was not what was desired with all the other functions happening and no time allowed for optimization.  It will be a follow-up feature. Instead I used it for randomization of the head and firing sequence which made it less like an automaton from cheesy restaurant.

Due to limited time, I decided to basically use an Arduino DUE because it had 54 GPIOs to cover the 32 LEDs I wanted to sequence and still have room for the servo and the condenser Microphone pickup. I spent a considerable amount of time soldering current limiting resistors for the LED’s as well as a transistor driver for the larger and brighter white LED’s which would be too much for an Arduino’s GPIO.

Each LED had heat shrink and wire run all down to the base of the NERF Blaster and came together in a ribbon cable that fed back into the backpack.  On the Backpack ( sorry limited pictures before I handed off to the owner), I had to carefully solder the resistors and feed them through holes. I took apart a Dewalt large capacity chalk line to create the industrial pack for Rocket. The wind-up hole was perfect for the color LED and the Circular LED fit perfect around it.  All of this was thread through the outer casing and then soldered them onto  a board on the inside and another ribbon cable mated with the Arduino.

I only had a mini servo. To maximize the movement, I created a metal frame from a robotic’s mechanical assembly kit and mounted it on the spindle of the servo. I tested the proper placement inside the puppet and found the ideal placement was inside the nose of the raccoon to get the most movement.

I coded up the arduino and ran several tests with 3 AA batteries.  I was able to get about 4 to 6 hours of life before the batteries needed to be changed

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I had a working Halloween prop for my friend in time for her to do some last minute augmentations ( she made is jump suit). She took it up to Salem MA to join in the fun. She got a lot of strange looks and wonderment from her little animated Rocket.