SmartCard PC Serial Reader / Writer (Phoenix) Electronic Circuit
The MAX232 converts the RS-232 levels (about +10 and -10 V) to TTL voltage (0 and +5 V) and vice versa without requiring anything else than +5 V power supply. This chip contains two TTL->RS-232 and two RS-232->TTL drivers and needs four external 1 uF capacitors in order to generate the RS-232 voltage internally. The adapter electronic gets its power supply from the smartcard reader device VCC line or you can use an external 5 V supply if you wish.
The following description may be used in order to connect computers to ISO 7816 compatible chip card systems (e.g. GSM mobile phones or other pay-TV decoding systems) if they also use asynchronous transmission. For smart card systems which use synchronous transmission (e.g. most phone cards) the interface described here will need some modifications.
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Our design supports standard MP3 file formats with a bitrate of 128Kbps. The decoder chip that we used supports rates from 8Kbps-320Kbps, but we decided it would be simpler to support one bitrate, and then expand the design to support other rates. Our decoder required the incoming bitstream to be equivalent to the decoded bitstream (128Kbps).
Here is a teleremote circuit which enables switching ‘on’ and ‘off’ of appliances through telephone lines. It can be used to switch appliances from any distance, overcoming the limited range of infrared and radio remote controls.
An ordinary automatic room power control circuit has only one light sensor. So when a person enters the room it gets one pulse and the lights come ‘on.’ When the person goes out it gets another pulse and the lights go ‘off.’ But what happens when two persons enter the room, one after the other? It gets two pulses and the lights remain in ‘off’ state. The circuit described here overcomes the above-mentioned problem. It has a small memory which enables it to automatically switch ‘on’ and switch ‘off’ the lights in a desired fashion.
PICADC - a free, PIC based "intelligent" A/D converter
The PICADC is a simple 12-bit, 8-channel analog to digital converter (with 4 additional digital inputs), which may be connected to the PC through the serial interface (RS232). The sequence of sampled channels, and sampling frequence are programmed by the PC.
Mains sockets switched automatically by a Control Socket Up to 1000W switched power
This circuit consists of a Trailing Socket (also called Extension or Distribution Socket) or similar device where two, three or more sockets (depending on the box dimensions and on constructor's needs) will be powered only when a current flows in the Control Socket.
Here is a circuit for using the printer port of a PC, for control application using software and some interface hardware. The interface circuit along with the given software can be used with the printer port of any PC for controlling up to eight equipment.
For around $30 in parts and a good amount of patience, you can have a completely open source and hackable mp3 player ready to go. It can be modified to accept serial commands, be embedded in an art project, used as the voice of your next smart talking robo-sidekick, or filled with music and used as is. Put in whatever size card you want, up to the theoretical limit of the MMC format! All the source and schematics are here for free as part of the Creative Commons.