Saturday, 2 July 2016

LM317 Benchtop power supply

Yet another LAB benchtop Power Supply.

This time with the legendary LM317, one used as current limitter and the other as voltage regulator. The enclosure from an old Delta Elektronika Power supply is used as housing.
The poor thing was blown apart by an mad Scientist. As a benefit i could use the original front panel.

I used an TL431 with an BC547 to create an current source. This is necessary to apply an negative
voltage so the power supply can regulate down to 0 volt.


When i tested the power supply i found two issues: When switched on, it gave an overshoot of the
output voltage of several volts. When switched of, the same problem accured. I designed an extra
circuit to solve this issues.

The circuit ensures that at power up a 1 ohm
power resistor is in parallel with the output.
Afther about 0.5 second a relay releases this
load. At power down it comes back quickly so
the overshoot at power down is also prevented.

An inside view of the power supply. The extra circuit is not yet mounted.

Wednesday, 17 February 2016


Also know's as a windspeed meter. 
I use an harddrive motor as encoder. The bearings are very good.  
Still working on it, but i tested the motor with the electronic's and that look's promissing.

                                                     Mechanical drawing (topview)

The motor generate's 3 pulses per revolution. The motor consist of 3 winding's and generate's an
3 phase sinus on it's coil's.
I only use one coil which is measured with an comparator with feedback. 
A oneshot is used to give pulses with a steady width so it's easy for an microcontroller to measure.


Test setup 

I used drain pipe end cap's to mount the motor and also to protect it against rain.

Violet trace: output from the motor
Blue trace:   output from the comparator
Red trace:    output from the Oneshot.

Tuesday, 22 December 2015

LM723 Bench Top Power Supply

Because the result with the XL4005 was a disappointment, i decided to make a bench top power supply with the "work horse" of power supply chip's. The LM723.

This is it for now.............

Monday, 21 December 2015


Welcome to my Blog.

Several little project's i did and do with electronic's and more.

HTML tutorial
500V Power Supply
HTML tutorial
30V 2.5A Benchtop
Power Supply
HTML tutorial
LM723 Bench Power Supply
HTML tutorial
Remote Controlled Robot

HTML tutorial
HTML tutorial
Tube amplifier AC30
HTML tutorial
2.6KV Power Supply
HTML tutorial
Delphi 7 stuff
HTML tutorial
Lazarus Free Pascal


HTML tutorial
Class A JLH Amplifier

HTML tutorial
Hide The cables


LM317 Benchtop


Wednesday, 9 December 2015

PCF8574 Controller

Actually i made the same program in Delphi7.
Some one asked my if i could change the application.
But after a reinstall of windows on my computer i couldn't find a free download anymore.
This is how i came up with Lazarus aka freepascal.

I improved it a little bit. It's now possible to set the comport. And also the address of the I2C
device. An ini file is used for this purpose.

Toggle Bit 0

Toggle Bit 1


High voltage power supply 2.6KV

Designed for an He3 Neutron counter.

The transformer is ripped from an Electronic Fly swatter.
The UF4007 diode is the fast equivalent of an 1N4007.

For the 200M feedback resistor you should use one which is designed for high voltage. If you can't find one, it's possible to connect 10 resistors of 20M in series.

To avoid electrocution the opamp is added to create
an monitor output.