Printer Port 256 Relays 16K Dot Matrix
Using this circuit on Printer Port, one could drive 256 Relays or 16K LEDs as Dot Matrix display. It can be used to drive a Large size multiplexed LED dot matrix display or Latched...
Simple Water operated relay
This was done in my early days, i have upgraded it, it ought to work, reduce the number of transistors to make it less sensitive, also a lower value in place of 10M will...
What is a Relay – Jim Asks
A text chat in long ago from my email records – 2007) Jim: hello, delabs: hello Jim: i have a Small problem,it’s about relays.me: would u pls give me an information about relays,pls give...
555 multivibrator like power oscillator
This is dual 555 multivibrator like power oscillator. This is my contraption and conception but couple of decades old. It appears to have errors. It worked but the document fixing after design worked, not...
Soldering Iron Tip
Can I use stainless steel to replace a defective soldering iron tip? mail from EA Soldering iron tips are mostly alloys of copper. the thermal conductivity of steel is poor. buy a soldering iron...
Passive volume control
please if you don’t mind I need to help to find a control circuit for volume of speaker 4 ohm or 8 ohm located in the another room far away of cassette or CD...
Seven Segment LED display
how is the circuit for driving a seven segment led mail from EA A 7 segment LED display is used to display a number 0-9 using 7 LEDs, The circuit you design must have...
Winding Transformers and Coils
i would need your help in designing transformers for rechargeable lamps. i really don’t understand what the dots in front a coil stands for. all help (including pictures) would be really appreciated. my own...
