Dual Polarity Power Supply
Two versions of a dual polarity power supply with printed circuit board artwork. The supplies are built around the popular LM317 & 337 complementary voltage regulators which offer very high ripple rejection as well as short-circuit and thermal protection.
A battery-powered microphone preamplifier and microphone wand for acoustic tests and recording. The preamplifier features 20dB of switchable gain and a clipping indicator,
Jason Neals DIY Audio and Electronics
An interesting website with many photos of electronic projects. There are not many projects but the description and photos and documentation are very useful for learning the art of circuit design.
The standard buck regulator circuit delivers a +5V output. This is a rather straightforward circuit and will operate with a wide spread of component values. Optimal values should be selected however to get minimal ripple, minimal noise to the power source, maximum efficiency etc. Note that the quiesent current is about 10 to 14mA.
Experiments with the LM2575
Here is a nice way of using this regulator, this can be used for CMOS opamps as you have a -5V too. That means a portable instrument may find this design useful.
The TI Datasheet Layout Guidelines
LM2575 – Step-Down Adjustable Voltage Switching Regulator with Output Enable
The Spirit of Hacking and Fixing, Giving back Life to Old Instruments.
Fluke 8050A LCD display replaced with LED seven-segment
“Recently I was able to cheaply buy a second hand Fluke 8050A made in the early eighties. It is a nice 4.5 desktop digit meter, but a typical problem seems to be that the LCD wears out and goes black. Replacement LCD displays are hard to find, not cheap and probably lead to similar problems in due time.”