Fisher Price #816 Record Player Repairs
Does your battery-powered Fisher Price record player have speed problems? Does the sound cut out all the time? These are my fixes.
Resources
Bluetooth As A Generic Audio Link
Can Bluetooth A2DP transmitters and receivers be used to make a reliable generic audio link over long distances?
Improving the Sparkfun MP3 Trigger
The inexpensive MP3 Trigger from Sparkfun does basically everything that “industrial MP3 players” can do. Unfortunately it has some rather annoying flaws. Here are my remedies.
Umbrellas as Parabolic Speakers
My first attempts at building portable parabolic speakers using parabolic photo umbrellas.
Take Apart An Electret Mic Capsule
How to disassemble an electret capsule and put it back together without ruining it.
Hydrophone Experiments
An underwater microphone using a common mic capsule and silicone sealant. It has relatively flat frequency response without the resonant “honk” of the piezo disc used in most DIY hydrophones.
Alex Rice Piezo Preamplifier
Alex Rice designed a phantom-powered preamplifier for piezo contact mics and hydrophones. It sounds great but his site is offline. I posted his files and made some changes of my own.
Inductive Pickup Experiments
Use the coil of wire from an old relay to listen to the electromagnetic world of modern machines.
VLF Natural Radio Experiments
“Natural Radio” is the low frequency residue of lightning strikes and space weather. After building a simple preamplifier circuit, you can tune it via the mic input of any recorder.
Low-Noise Binaural Mics (Primo EM272 and PUI 5024)
How to make wonderful low-noise binaural mics from Primo EM172 capsules for under $20/pair.
Marantz PMD660 Headphone Jack Fix
This popular Marantz audio recorder has a particularly fragile headphone jack. Here is a step-by-step tutorial on how to fix it.