R5000 Receiver Interface:  This circuit is a modified version of an original interface on QSL Net. It is a fully isolated interface allowing computer control of the Trio/Kenwood R5000 receiver. Separate software is needed to control the receiver.  (added 10/05)

Radio Clock for PC's:  (electronic circuit added 4/05)

RAID Controller Card:  Intersil Application Block Diagram  (app note added 6/06)

Read isolated digital signals Without Power Drain  :  11/26/04  EDN Design Ideas  /  (added 1/05)  Although optocouplers offer designers a straightforward method of establishing galvanic isolation between circuits that operate at different ground potentials, they do not provide an ideal approach

Reference Board User Guide for PI7C8152:  Pericom Semiconductor Application Note # 069 (app note added 02/05)

Regulator Circuit Generates Both 3.3V and 5V Outputs from 3.3V or 5V to Run Computers and RS-232:  DN71  Design Notes (Linear Technology) (app note added 6/06)

Remote Monitoring System Sends E-mail via SMS:  App Note 3297: Maxim IC  (application note added6/06)

Replacing Dedicated Protocol Controllers with Code Efficient and Configurable Microcontrollers-Low Speed can Network Applications:  National Semiconductor Application Note   (app note added 2/06)

Replacing the Intel 21150 or PLX PCI6150 with the PI7C8150:  Pericom Semiconductor App Note # 079 (app note added 02/05)

Replacing the PLX PCI6150 with the PI7C8150B:  Pericom Semiconductor Application Note # 080 (app note added 02/05)

Reset card eases µP troubleshooting:  10/26/95 EDN-Design Ideas / (added 2/06)   The circuit in Fig 1a generates repetitive system resets to 68XXX processors. These resets allow you to troubleshoot power-up problems using a scope instead of a logic analyzer or storage scope. This reset card, which you can build for less than $10, consists of a DIP switch, a resistor module, and an AMD MACH210 complex PLD (CPLD). The switch settings allow you to set the time delay between resets, enabling you to loop on and observe only the first few power-up processor operations or as many as you want. The resistor module pulls up....

Reset ICs create sequenced or long resets :  11/20/97 EDN Design Ideas – (added 2/06)  

Resistor implements half duplex RS 232 with echo:  11/24/99 EDN Design Ideas /  (added 2/06) 

RGB Video Switching:  Pericom Semiconductor App Note # 004 (app note added 02/05)

ROM Emulator:  This is a very simple ROM emulator. It can only "Load and Run", because reduced unnecessary functions and reduced board size, so it is good for portable use.  (added 10/05)

'Rounding Off' a square wave :  ASCII format (added 3/03)

Routine provides four COM port recognition:  02/01/96 EDN-Design Ideas / (added 11/05) 

RS 485 repeater extends standard's reach :  05/26/94 EDN Design Ideas /  (added 11/05)

RS-232 Autobaud for the PIC16c5x Devices:  Microchip Application Note Published 1-Apr-99   (app note added 2/06)

RS-232 DB-9 Switch-to-Flip between Two Serial Ports:  (electronic circuit added 4/05)

RS-232 Interface Circuits for 3.3V Systems:  DN75  Design Notes (Linear Technology) (app note added 1/06)

RS-232 Laser Transceiver #2:  (electronic circuit added 4/05)

RS-232 Line Driver Power Supply:  National Semiconductor Application Note   (app note added 2/06)

RS-232 Line Monitor and Loopback Cables:  (electronic circuit added 4/05)

RS-232 OverVoltage Protection Circuits:  (electronic circuit added 4/05)

RS-232 Port Monitor:  (electronic circuit added 1/03)

RS-232 Powered Temperature Sensor:  App Note 3424: Maxim IC  (application note added6/06)

RS-232 Protocol Analyser:  (electronic circuit added 4/05)

RS-232 Serial Port Buffer Circuit:  (design circuit added 8/02)

RS-232 Surge Protection #2:  (electronic circuit added 4/05)

RS-232 Surge Protection:  (electronic circuit added 11/05)

RS-232 to IRDA Convertor using Vishay Toim3232:  (electronic circuit added 4/05)

RS-232 to TTL Cable:  (electronic circuit added 4/05)

RS-232 Transceiver with Automatic Power Shutdown Control:  DN30  Design Notes (Linear Technology) (app note added 1/06)

RS-232 Transceivers for Hand Held Computers Withstand 10kv Esd:  DN64  Design Notes (Linear Technology) (app note added 1/06)

RS-232/485 Converter has Automatic FLow Control:  04/12/01 EDN-Design Ideas  / (added 4/02) / RS-485 communications can provide longer range and better noise immunity than RS-232, as well as multidrop capability. Because it does not have separate transmit and receive lines, RS-485 requires flow control. RS-232/485 converters often use one of the RS-232 handshaking lines to control direction, but several communications-software packages do not support flow control. This circuit an RS-232/485 converter that uses the transmitted signal itself to control the flow.

RS-232/DALI Bridge Interface:  Microchip Application Note Published 26-Apr-02   (app note added 2/06)

RS-232: Lowe HF-225 Interface:  (electronic circuit added 4/05)

RS-232c Circuit has Galvanic Isolation:  02/04/99 EDN-Design Ideas  / (added 5/03)  You can obtain longer transmission distances with the RS-232C interface if you use galvanic isolation between the two linked terminals. Galvanic isolation also eliminates problems arising from disparate potentials between terminals. Using two MAX860/861 ICs and two TPL2200 optoisolators, you can obtain galvanic isolation for three-wire transmission without external supplies (Figure 1). The MAX860/861 circuits, which generate two voltages of different polarity, regardless of the polarity of TxD, which provides the supply voltage, are the basis of the design....

RS-232c Communication using UART:  Toshiba 870X Series Application Note  (app note added 2/06)

RS-232c Handshake Lines Transfer Data Frames:  10/23/97 EDN-Design Ideas  / (added 3/03)   

RS-232c Interface Meets Telecommunications Safety Specs:  09/28/95 EDN-Design Ideas  / (added 3/03) RS-232 isolation circuit

RS-232c Interface with COP800:  National Semiconductor Application Note   (app note added 2/06)

RS-232c Level Converter using Transistors:  (circuit added 7/02)

RS-232c Level Converter:  (circuit added 7/02)

RS-232c Line Driver IC Drives Power MOSFET s:  10/24/96 EDN-Design Ideas / (added 6/06)   -Easy to effect an interface between power MOSFETs and TTL circuits

RS-232C Link Monitors Animal Activity:  11/06/97 EDN-Design Ideas / (added 3/03)  

RS-232c Powers and Reads 8 Bit Switch Matrix:  04/11/96 EDN-Design Ideas  / (added 3/03)      

RS-232c Serial Port Scans Remote Keypad:  12/04/97 EDN-Design Ideas / (added 5/03)  

RS-232-to-RS-232 Port Powered Optical Isolator:  Brochure with schematic in PDF format / (added 7/02)

RS485 Like Multi Drop Bus with half Duplex Serial Protocol:  (electronic circuit added 7/03)

RS485 Repeater Extends Standard's Reach:  05/26/94 EDN-Design Ideas  / (added 3/03) RS-485 specifies communications for distances up to 4000 ft. This limit is the consequence of losses in the twisted pair used to carry the data. Beyond 4000 ft, skin effect and dielectric losses take their toll, attenuating the signal beyond use. Fig 1 shows a simple RS-485 repeater. Two RS-485 transceivers connected back-to-back relay incoming data from either side. A pair of cross-coupled one shots control the data flow so that only one transmitter turns on at a time. A 1-to-0 transition at the output of either idling receiver signifies...    

RS485-like multi-drop Bus with half duplex serial protocol:  (electronic circuit added 4/05)