Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Did I just increase DS1022CD bandwidth four times?

Probably you are already familiar with famous DS1052E hack where guys were able to double and even triple bandwidth. It happens that on my table is DS1022CD scope with 25MHz analog bandwidth. And this hack doesn’t apply to my model. We all know that same series Rigol oscilloscope models tend to have identical hardware whether they are 25MHz, 50MHz or 100MHz analog bandwidth. Of course, sampling rate (400MHz) stays the same. So it all lies in the software. I felt that someone would figure out how to do this with this pretty old oscilloscope. And here it is – a hackaday pointed to a piece of great news – simple way of changing the model from DS1022CD to DS1102CD which converts analog bandwidth from 25MHz to 100MHz. This is quite a step without spending a penny. –>

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IR remote control extender

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 in other room.

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LEDComm: Bidirectional Communications using LEDs

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 duplex communication is possible when using 2 LEDs – still very cheap even compared to the IR pairs available in the market this is a steal if you can make one run on your project.

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Fast and dirty way reversible motor control

THe nothinglabs in his instructable explains how to build the simplest DC motor controller. It supports PWM speed control along with direction and enables control pins. Due to its rugged hardware design, it withstands peak five amps or continuous 2.5 amps without the heatsink. The controller is built by using a couple of TIP120 Darlington transistors, two 220 ohm resistors, and standard 12 relay. It is assembled without the need of PCB – directly on the relay itself. So if you’re looking for the fast solution, this may be a savior.

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Generating complex sound waves on PC

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.

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Inside Compact Fluorescent Lamps

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. Be sure to take safety precautions as each lamp tube contains some mercury gas which is hazardous. In other hand, if you are real electronics hobbyist, then you can simply harvest lamp circuit for some valuable parts for other projects. Over all it is useful to know some general principles…

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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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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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