Delay power on circuit

I am working on a project that uses an analog meter and to give that extra retro feel to it when I turn it on I wanted a delay power on circuit to simulate a tube warming up. I did a quick search and seems everyone uses 555 timers. I know there is a simpler way to do it so I pulled out a book a friend gave me titled “Guidebook of Electronic Circuits” ISBN: 0070404453. The book has 3,600 circuits from the 70s so it should have something. I found the protection circuits chapter and saw one that is meant to protect solid state rectifiers. The circuit uses a 2n3055 NPN transistor a capacitor and resistor. Since I want to use this to switch on a LED that runs on DC current I decided to reverse engineer it and use a 2n3904 NPN transistor, 1000uF 10Volt cap and a 10Kohm 1/4watt resistor. Sure enough it works dandy and with the voltmeter it pushes out 2.65v load with 3.3volts going int the circuit.

Power Delay

Sorry for the crude drawing.

It works very well and you can use bigger or smaller capacitor. The higher the uF the more delay you get.


Arduino Logic Analyzer

A while back I bought a Arduino Uno and never found a good enough project for it until yesterday. I found a simple Logic Analyzer project. Sadly it isn’t a all-in-one unit. You still need a PC to control it. The project is called Arduinolyzer.js. It was a pain in the butt to get NodeJS working in Windows XP. Yeah I know I’m running XP but this is on a old system I use for tinkering. Anyway, after I fixed the broken Windows Installer I was able to install NodeJS just fine and within minutes I got a functional PC controlled Logic Analyzer.

DIY PC Controled Oscilloscope

I built an easy single channel oscilloscope adapter that turns a typical PC into a functional oscilloscope. It is very simple to build and the software is also free. I searched around and found the perfect setup then I tweaked it.

oscilloscope probe

No pot is needed to tweak the voltage. Four 1N4148 diodes handle the protection so you won’t kill the sound or computer. Do not go over 5 volts DC when testing a circuit! I wouldn’t try probing AC current as well!

When I was searching up on the subject I noticed everyone is using typical audio/speaker cable. I find this as a “no no” since you are around AC current noise the system will pick it up. I used an old TV coaxial cable since it is shielded and I have a crap load of it. Just cut off one end and solder a headphone jack on. Since I made a single channel I only used the tip and ground of a stereo headphone jack. You can easily turn this into a two channel but you will need two coaxial cables or build two single channel adapters and use the Mic and Line-in on the sound card. On the adapter side I used a coaxial extension so I didn’t have to strip both ends of the cable, also I can make a longer cable in the future or whatever. Also for the input I am using banana plugs so I can use my multimeter probes. If I make another one I’ll use a BNC connector so I can use a real oscilloscope probe. For the case I used an old GrandStream ATA case. The circuit is small enough that you can toss it into anything such as a TicTac box or even a Altoids box.

The software is called Soundcard Oscilloscope. It works very well and I can easily run it on an old AMD Athlon XP 2000+ with WindowsXP. The software isn’t freeware but it is free to use for private use.


I’m in the market for a oscilloscope. I don’t need anything fancy or new and it would be awsome to get a vintage tektronics 545 tube oscilloscope but that is wishful thinking. Way I see it is if it works then hell yeah!