Schematics / Medical
Low Cost Hearing Aids
For me, the realization came about seven years ago. My wife, who was sitting to my left, asked me, "Are you going to answer that?" As I turned my head to look at her I began to hear the phone ringing behind me. That was the day I decided that I had to address my hearing problem....
Heartbeat Monitor (HeMon)
One day whilst walking through the town centre in Manchester (probably on the way to Maplin!), I came upon a heartbeat measuring machine - here, you had to place a finger into a "thimble"-like sensor, and hey presto, your hearbeat was measured and shown on a large LED display!...
Earclip Pulse Monitor 
This is a circuit that was designed by Jim Thompson of Analog Innovations. It uses a single LM324 quad OpAmp and a hand full of discretes to generate a TTL/CMOS signal that for monitoring the subject's pulse....
Cranial Electrotherapy Stimulator
CES is the most popular technique for electrically boosting brain power, and has long been prescribed by doctors, mainly in the USA, for therapeutic reasons, including the treatment of anxiety, depression, insomnia, and chemical dependency....
An Inexpensive X-Ray Machine
From an old radio tube, some copper wire, and other inexpensive materials — total cost: roughly $20 — you can construct an X-ray machine that will make good pictures through an inch of wood. SAFETY MEASURES THAT YOU MUST OBSERVE. Notes on Röntgen's invention. Highlights of X-ray theory....