Repository-circuits
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You can add as many extra zones as you like to the Transistor Burglar Alarm System. The first circuit is designed to be used with the usual types of normally-closed input devices such as - magnetic-reed contacts - micro switches - foil tape - and PIRs. The.... -
You can use a Cmos 4001 or a Cmos 4011 in this circuit. They have four - two-input - gates. In each case - the two inputs are joined together. So the gates are being used as simple inverters. = This means that when the two inputs are high - the output will.... -
This is a two-zone alarm - with automatic exit, entry and siren cut-off timers. It can be triggered by the usual types of normally-closed input devices - such as magnetic reed contacts - foil tape - PIRs etc. I`ve used a 12-volt supply in the diagram - but.... -
The key you`ve connected to "E" is used to energize the relay. And the four keys you`ve connected to A, B, C & D - are used to de-energize it. All the other keys on the keypad are connected to "F". = When "E" is pressed - current from the "Com" terminal.... -
This circuit uses two signal generators to simulate an Amplitude Modulated RF carrier wave. The output can be used to simulate the response of LC and tank circuits. Two signal generators are used in this circuit, one representing a high frequency (200kHz) RF.... -
This is a zine dedicated to electronics circuit diagrams, diy (do it yourself) electronics projects, electrical electronics data sheets, and micro controller projects for hobbyist, students, consultants and product designers... -
This interface design comes a long way. This is in fact the first microcontroller design I`ve ever started. Somehow it kept going with me during past few years. I probably drew the first lines of the schematics diagram of the first prototype in early 1998..... -
The inputs of the 74LS153 chip were mixed, which caused the address block decoding to fail. By now, I know of two Commodore 64 (mine and Pekka Pessi`s) where this expansion has been built, and of four Commodore 128s (of which two expanded by me, and the.... -
A block diagram of the Commodore 64 internal power supply (how the +12V, +9V and TOD clock signals are generated from the 9V AC input). Taken from the SAMS C64 Troubleshooting Guide. Commodore 64 schematic diagram, scanned with 360 DPI, 2 colours. This seems.... -
VIC-20CR rev. D (NTSC, new design). Assy number 251027-01. The PAL model has a crystal frequency of 4433618 Hz, and there is an extra 56pF capacitor on the solder side of the board, soldered parallel to R5... -
This circuit came out of some work I did for the two antenna analysers which are described elsewhere on this site. Those instruments both include an RF signal generator. This is used as the signal source to drive the impedance bridge and detectors used to.... -
Accessories built so far include a linear power supply, a switchmode power supply, a tuning aid, and a headset. An antenna tuner and SWR meter will be described later. In order to operate the new transceiver, I needed a power supply. I began by building a.... -
As equipment becomes increasingly more compact, designers are often obliged to follow suit by reducing the size of displays. At some point, the usefulness of the display can become compromised. I, for one, dislike having to peer intently at tiny displays in.... -
This compact RF oscillator covers the entire 0. 4 - 30 MHz range in a single sweep of the dial and has a terminated 50 ohm output of more than 300mV across the entire HF band. Most signal generators use a series of ranges to cover the HF band. This.... -
A 80m (3. 5 - 3. 9 MHz) SSB transceiver using a Collins 455 kHz mechanical filter in the IF chain. Such designs need some good front-end receiver selectivity in the form of at least a couple of selective tuned circuits. I`m also planning to build a simple.... -
Results are shown on an analog VSWR meter. The design was originally published in `Break-In`, New Zealand`s amateur radio magazine in Sept/Oct 2005, and is republished here with the permission of the editor. Note: `Break-In` is a term used in amateur radio.... -
A couple of cheap CMOS ICs are used to digitally generate audio sinewaves across a wide range in this compact battery-powered test instrument. The oscillator features both unbalanced and balanced outputs. I use signal generators of one sort or another all.... -
This instrument measures complex impedance over the 1. 6 - 33 MHz HF spectrum. It also calculates and displays the VSWR of the impedance referenced to 50 ohms. The most common application of the meter is as an antenna analyser. The design was published in.... -
Two cheap CMOS ICs and a few transistors was all that was required to rebuild my elderly TTL automatic morse keyer into a low current lightweight battery powered iambic morse keyer. Sometime over the past year or two, my elderly Accu-Keyer gave up the ghost.... -
After I built my KN-Q7 kitset 40m QRP single sideband (SSB) transceiver, described elsewhere on this site, I went on to build a matching low power "Z-match" antenna tuner and a sensitive SWR meter. For some reason, I found I needed three hands to tune this.... -
This manual is for use by authorised Sinclair dealers. engineers and representatives as a guide to rectifying faults on the Sinclair ZX Printer. Repair/renewal procedures are limited to those which are specific to this printer; standard procedures for the.... -
This is a general purpose remote control project with using programmable PIC microcontrollers. Schematics are shown for using infrared (RF) or radio (RF) media. If you are not familiar with microcontroller programming, you can use fixed encoder and decoder.... -
The memory system design: the detailed timing waveforms for a static RAM component, and the design of the register and control logic that surrounds the memory subsystem, making it possible to interface the memory to the rest of the digital system. But first,....
New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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