This is mainly a rant, but it's completely true.
Square Wave Generator (Adjustable pitch approx. 50-400Hz) Skill level to construct: Beginner Parts list:
C1, C2 3.3uf / 25v tantalum capacitor C3 6.8uF / 25v electrolytic cap Q1, Q2 MPS6534 PNP gen.purpose amplifier transistor R1 680 Ohm 5% 1/8 watt carbon film R2 220 Ohm 5% 1/8 watt carbon film R3 18 K 5% 1/8 watt carbon film R4 1.5 K 5% 1/8 watt carbon film R5 5 K mini-potentiometer R6 10 K mini-potentiometer J1 1/8" mini phone jack J2, J3 9v battery connector T1 Mini audio matching transformer: HiZ C.T. - LoZ 2.5" x 4" green epoxy/fiberglass PC board
2.5" x 4" stamped aluminum case. Looks like an "Altoids" candy mint tin box, just a little bit bigger.Would you believe that If I built this and sold it, it would be worth $400.00 - $500.00 ?!!? No kidding! I discovered this recently when my Cooper-Rand "Artificial Larynx" died. I had to price a new one and my insurance comany was balking at preauthorizing purchase of the unit (I lost my larnyx to cancer several years ago and I'm forced to use one of these devices to generate the basic vibrations for my speech).
It's a butt-ugly cheap looking piece of 60's design marketted by Luminaud, Inc. It's got far fewer parts than a cheap 5-buck 60's transistor radios, housed in a tin-can case I'd be embarrassed to let a 10 year-old put his first electronic project in. And yes, I believe that Altoids sells their "curiously strong mints" in a higher quality case for $1.95 Sell it as a "Speech Prosthesis" however, and these dozen common, cheap parts in a tin-can are worth a vastly greater sum than their weight in precious metals.
I was quoted between $400.00 - $550.00 for a new unit. One dealer offered to sell me a used one for $325.00. Two offered to repair my faulty unit at fixed rates of $100.00 and $149.95 respectively.
Rather than maxing out my credit card, filling out the forms and hoping that my HMO would reimburse me, I fixed mine for in 10 minutes for less than a dime.
All I did was replace both transistors with a couple 2N3906 I had lying around. Not quite the same spec, but since I paired them up, they worked. I suppose I could even order all the parts to build a new one one from Mouser or Jameco for less than $5.00 *retail*
Maybe I should use a slightly different design to get around patent infringement and sell them myself for less than half what these crooks are soaking the medical insurance companies and HMO's for. I'd still be making a bundle. Naw... Wouldn't work. I don't have the money up-front to bribe the FDA or whatever US federal agency that has to "approve" them for medical use. Oh well..