To start old Optrex DMC50264N LCD module you need to get +24V LCD bias voltage? Where to get it if you have only low voltage 3 … 5V? As LCD module drains very low current, it is possible to build very small DC/DC converter. There are lots of chips designed for this. I used MC34063, […]
One of the popular programs for PCB tracing and circuit diagram drawing is Eagle from Cadsoft. The software is available for Windows, Linux and Mac operating systems.
Freeware version of software has some limitations: The usable board area is limited to 100 x 80 mm (4 x 3.2 inches), only two signal layers can be used […]
Got some bad security video cameras for recycling. Few color ones made by Philips, two Sanyo and others KC-263C and KC-383C. It is mid and high resolution black and white CCIR video cameras.
Security cameras' bodies and some generic brown Pokemon.
The KC263 and KC383 are powered from the mains power. It can handle 85…265V AC. […]
Connect pulse generator from older post to your audio amplifier. Set volume to something in the middle. Connect oscilloscope to the output of the amp with dummy load.
You will not see ideal square signal in the output, but all these distortions can describe your audio amplifier.
As there are lots of images in this post and […]
For further audio amp analyze we need square waveform generator. I can use my generator, but we can build one using very common TTL chips. We can use any 74XXXX chip which can be combined to “NOT" logic element. Most common chip is 74LS00. In my breadboard I used 74LS04… I used all idle “NOT" […]
How to measure real output power of audio amplifier. Sometimes on some cheap audio devices you can see magical numbers like 1000W or something, and device is handheld. It is not real power, it is bullshit.
Attach dummy load to audio amplifier load. The resistance of the load must be equal to resistance of your speaker. […]
I removed few Optrex DMC50264N LCD modules with few buttons from some old laser printers. These modules are controlled by Mitsubishi M50530-026FP and M50521FP chipset. It is 4 lines 16 symbol special LCD module controlled by master CPU only by three wires. It is very simple serial to parallel converter made with the help of […]
In older post I wrote that long time ago I built my first tube amp. Today, in old magazine, I found the schematics. As I remember, the output stage was working, but I made some mistakes in pre-amp. I left amp for very long time and my mother decided that it was junk and threw […]
For my audio amps I needed some small generator just for testing. And I also had MAX038 chip sample. Here is the abstract from datasheet:
The MAX038 is a high-frequency, precision function generator producing accurate, high-frequency triangle, sawtooth, sine, square, and pulse waveforms with a minimum of external components. The output frequency can be controlled over […]
In German (sprut.de) pages I found small schematics for caps meter. This schematic is designed for electrolytic capacitor metering. According to author, device range is from ~10µF to ~65 500 µF. This is not very accurate meter, but it is suitable for testing big electrolytic capacitors used in computer mainboard. And you must remember, that […]
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