Electronics, telecommunications and IT
by: Daniel Olteanu
Hello, I'm Daniel Olteanu, electronics and telecommunications engineer.
On my site you'll find some usefull circuits I've designed over the time, and someones from the internet.
RJ45 UTP/STP cable tester the emitter
RJ45 UTP/STP cable tester the receiver . You may watch this cable tester functioning in the next picture.
Benchtop dual power supply 30V 1A . I have designed and built this power supply in 1992. It has double short circuit protection: first by limiting the output DC current, and the second by completely disconnecting the AC voltage at the transformer's secondary winding.
This second protection circuit it's not figured in the schematic diagram.
The AC disconnect is performed by means of an optocoupler and a timing circuit.
The picture shows the square black pushbutton, with a small green LED on it, and two yellow LEDs at the left and right.
The yellow LED ON indicates that a short circuit condition it is present on either V+ or V- section.
A few secons after the short circuit ocurred, the small green LED turns ON and indicates that the relay protection disconnected the AC.
In order to reconnect the AC the pushbutton must be depressed.
This power supply never failed since 1992. I could hardly detect any ripple at the output.
My first small superheterodyne radio receiver Medium Wave-Short Wave . I have designed and built this receiver in 1985. Taking into account how simple it is, it has a very good selectivity and sensitivity.
www.elforum.ro Best romanian electronics forum.
