Turning Oscilloscope in to video monitor

This trick works best on CRT analog oscilloscope. The idea is to split a composite video signal into two separate X and Y signals that are fed to an oscilloscope (Tektronix 465m in this particular case). The signal split is performed inside an LM1881 chip that takes NTSC composite video signal and splits it into two sync signals that are fed directly to the scope. Signal intensity is generated via Z-axis input that is present on the scope. A composite video signal sent to z-axis input. The only problem of the scope video monitor is that the signal gets inverted, so the simple inverting buffer is used for the z-axis. The author encourages us to keep experimenting with video signals instead of copying stuff blindly.

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Transistor based FM bug in mint box

There are tons FM bugs all over the internet. You may find small, IC based ones, powerful, sensitive and so on and on. Take a look at this transistor based FM transmitter that actually fits in a mint box. This FM bug uses only widely accessible discrete elements. It even uses couple general purpose BC547 transistors that can be replaced with any other similar if needed. As voice input there is an electret microphone used which is sensitive enough. The carrier signal of FM transmitter is chosen between 88 and 108MHz. To see in detail how signal is amplified and mixed with carrier signal here. Whole FM bug is powered with single 3V coin battery which is a biggest part in transmitter. Anyway it fits Minty box nicely and is able to transmit audio signal over 25 feet.

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Smart resistor colour wheel

Probably you are tired of those resistor colour tables and small programs where you must trace the resistor value by colours. Rob got an idea to make it simpler, so he constructed a very simple paper wheel construction where you can turn them to match colors of resistor bands. Once colors are matched resistor value is right here – on the wheel itself. So download, print and assemble this simple resistor colour wheel project that actually fits in your pocket.

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EEPROM animation box

We used to see various LED matrix projects based on microcontrollers. But do we need one for playing simple animation effects? This can be easily done with simple parallel EEPROM chip. There are several things you will need to take care of. First of all EEPROM chip – any parallel EEPROM chip like UV erasable 27C256 will work. In this project an 8×8 LED matrix is used, so one frame occupies 8 bytes of memory. Using 32kByte EEPROM it can hold 4096 frames. To make EEPROM animation work, we need address sequencer, which has to strobe addresses in proper way. This is done with 12 stage ripple 4040 counters that are driven by simple 32kHz oscillator. There is also a nice small Delphi program available, which eases generation of images. Save them in binary format, burn to chip and enjoy EEPROM animation.

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Add button cell to a breadboard project

If you are developing any electronics project, probably you wanna prototype first to make sure it works as expected before building real boards. Low power electronics usually relies on smaller batteries – especially wearable, mobile where size matters. In this case you usually choose a button cell battery. When prototyping probably it is good idea to use same battery in breadboard. Question is how to attach it reliably to breadboard. Grathio labs provided a simple solution that saves time and money. They suggest to make coin battery holder out of binder clip that you can find in any office. This solution can be used to house one or several batteries depending on width of clip. Also it could fit different width batteries. Great idea can be so simple use it.

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