Category: Hacks

IR remote control has a limited range and doesn’t work when it is out of line of sight. But what if you need to control your appliances even if don’t see them. [Michail] suggest to build an IR remote extender that stands between your remote control and device to be controlled. Building one seems to be pretty easy task. It has to repeat everything you send. Repeater circuit design is based on Andy Collinson circuit. It is based on 555 timer circuit that makes overall repeater small and cheap. Repeater receives IR signal by TSOP1738 receiver. As you may know receiver demodulates IR signal by removing 38kHz. 555 timer is set up to generate 38kHz signal which is modulated by TSOP1738 output. Whole magic that simply works well. If you need to control appliance that is in different room you can simply locate receiver in your presence while transmitting LED…

Continue reading

Unlike most projects featured here this one does not really involve a specific microcontroller – since it can be used with any microcontroller having two available digital pins – both must be input output capable. This is not actually new – this paper as published July of 2003 yet we haven’t seen many projects using this as means of communication. This method is the cheapest wireless communication means that ive heard of – in terms of components just two LEDs and viola! Wireless communication! LEDs are usually light indicators but they too can be light detectors when operated in reversed bias mode it will act as if it was a photo transistor – neat huh? Both emitter and detector in a small low cost package – to switch the LED from forward bias to reverse bias mode one must switch the digital pins from low to high thus only half…

Continue reading

Most persistence of vision (POV) projects are very hard to time – questions arise one when to start the sequence of On’s and Off’s to make the pattern of lights. It’s not really that difficult to do the timing but it requires a certain skill and an awful amount of patience. Most of the existing POV units has a synchronizing signal – this may be a opto interrupter, a line sensor or even trip switches switch made out of dangling wires! To make it more sophisticated Rucalgary built a tiny POV with just seven LEDs  an ATMEGA48A  and a MMA7660 accelerometer from freescale – no he is not advertising its just way too cheap. The accelerometer is used to determine when to start displaying the messages – one more thing that separates this from most POVs is that it has multiple messages stored in an EEPROM – which the microcontroller…

Continue reading

Generating sound waves from PC sound card isn’t new ting. You can even download tons of software that allows generating various waves like sine, square, triangle waves on speaker output. Such sound generator gives quite good results that are acceptable in most situations like testing audio equipment or feeding complex signals in to your projects. There are some shortcomings here. The signal frequency is limited to 20kHz which his not that bad actually when speaking about audio. And there is a risk to damage audio card. Hobbydebraj have found that it is hard to add signal offset that would allow generating signals above 0V level. So he managed to build a simple circuit based on LM358 amplifier which gives ability to add an offset. Now using Matlab software he could generate any complex signal he wanted.

Continue reading

Today we use Inside Compact Fluorescent (CFL) lamps almost everywhere because they are rated to last much longer than standard light bulbs and consumes significantly less power (up to 80%). This luxury costs money and this is why it is annoying when CFL lamp goes off unexpected. We usually nervously throw it to a garbage like a piece of “sh…” and buy new one. But wait. If lamp isn’t broken or sealant is still in tact then the only problem is in electronics which sometimes can be repaired. Pavel Ruzicka has plotted his findings and experience on his page, where he gathered some information on various CFL lamps. These include detailed circuits and working explanation. In his experience everything starts from broken capacitor and then leads to following sensitive electronics. So if you think that your lamp is too expensive to throw away, then you can try to repair it.…

Continue reading

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.

Continue reading