4 Digit Keypad - This is an enhanced 4 digit keypad which may be used with the Modular Alarm System __ Designed by Ron J.
4 Digit Keypad Switch - This is a universal version of the Four-Digit Alarm Keypad. I'vemodified the design of the output section - to free up the relay contacts. This allows the circuit to operate as a general-purpose switch. I used a SPCO/SPDT relay - but you can use a multi-pole relay if it suits your application. __ Designed by Ron J.
4.5V to 14Vin, 3.3V AT 25A Vout Switches at 2MHz - A 2MHz, 3.3 V/25A step-down converter. The LTC3838/LTC3839 can operate at switching frequencies above the AM radio band (fSW > 1.8MHz). The high switching frequency permits the use of inductors of very small footprint, so that the entire circuit can fit within a 0.9in2 area with both sides populated. The peak efficiency is 95%, and full load efficiency well above 90% at 25A, even at a frequency of 2MHz. __ Linear Technology/Analog Devices App Note, Mar 29th 2012
4-Bit µPs A/D Converter Decodes Keypads Input - 10/13/94 EDN Design Ideas: Fig 1 shows a MitsubishI M50927-XXXSP/FP 4-bit microcontroller decoding a 4×4 keypad using only four digital i/O lines instead of eight. Saving four of a 4-bit µC's precious i/O lines couild be significant.4-bit µC's ADC provid __ Circuit Design by Ryoden International Shanghai Ltd, Shanghai, China
4-Digit Alarm Control Keypad - Alarm Control Keypads: This Keypad is suitable for the Modular Burglar Alarm. However, it has other applications. Pressing a single key will energize the relay. Entering the Four-Digit code of your choice will de-energize it. __ Designed by Ron J.
4-Digit Keypad Controlled Switch - Universal Keypad-Controlled Switches: This is a Universal version of the Four-Digit Alarm Control Keypad. I have modified the design to free up the relay contacts. This allows the circuit to operate as a general-purpose switch. I'veused a SPCO/SPDT relay - but you can use a multi-pole relay if you wish. __ Designed by Ron J.
5 Digit Alarm Keypad - This is an enhanced 5 digit keypad which may be used with the Modular Alarm System. This switch will suit the Modular Burglar Alarm circuit. However, it also has other applications. The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with 7 terminals will NOT do. Choose the five keys __ Designed by Andy Collison
5 Volt Momentary Operation Touch Switch - This simple circuit uses a single IC to form a nice touch switch circuit. A single transistor forms the remote active switch sensor. Multiple switches can be wired in parallel. The switch circuit can be located about 500 feet from the control circuit . . . Circuit by David A. Johnson P.E.-March, 2002
555 timer converted into pulse-width Modulator - 15-Feb-07 EDN Design Ideas: Added CMOS
switch enhances a PWM oscillator __ Circuit Design by Jordan Dimitrov, Tradeport Electronics, Vaughan, ON, Canada
555 Timer MonoStable using Pushbutton - The two circuits above illustrate using the 555 timer to close a relay for a predetermined amount of time by pressing a momentary N/O push button. The circuit on the left can be used for long time periods where the push button can be pressed and released before the end of the timing period. For shorter periods, a capacitor can be used to isolate the switch __ Designed by Bill Bowden
5-Digit Alarm Control Keypad - Alarm Control Keypads: This Keypad is suitable for the Modular Burglar Alarm. However, it has other applications. Entering the First Four Digits of your chosen Five-Digit code - will energize the relay. Entering the Full Five-Digit code - will de-energize it. __ Designed by Ron J.
5v Capacitance Touch Activated Momentary Switch - This circuit is discussed in more detail in the section on Capacitance Proximity Switch Technology. The circuit is powered from a standard +5v supply. it has both a source and sink output that change state whenever a metal button connected to the circuit . . . Circuit by David Johnson P.E.-July, 2000
5v Touch Switch - This simple circuit uses a single IC to form a nice touch switch circuit. A single transistor forms the remote active switch sensor. Multiple switches can be wired in parallel. The switch circuit can be located about 500 feet from the control circuit. . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2002
6v Solid State Switch Solar Charge Control - This is a Solid State Switch upgrade to the 6A, 6V Relay Based Solar Charge Regulator. Solid state switching provides longer life, smaller size and higher efficiency than a relay. in addition, the clock frequency may be doubled in order to better track battery load /charging requirements. The parts cost is essentially identical. One drawback__
7 Segment Display & Keypad - Since the output buffer ofP1 can sink 20mA (each output pin, but maximum iOL for all outputs was limited at 80mA) , thus we can use P1 to drive LED display directly. As shown in the circuit, Two common-anode 7-segment LEDs are connected to P1 with 180 Ohms current limiting resistor. Each segment of two LED __ Designed by Wichit Sirichote
70m Ohm Protected Load Management Switch - DN117 Design Notes __ Linear Technology/Analog Devices
8 Switcher Powers High-Performance µPs - 04/13/95 EDN Design Ideas: The circuit in Fig 1 delivers 8A for driving as many as two of today's high-performance, high-speed µPs. You can also optimize the design for lower current by changing a few components. Most systems use a low-current 12V bias supply and a poorly regulated high-current 5V to power the logic. However, __ Circuit Design by Chester Simpson, National Semiconductor, Santa Clara, CA
8 x 8 Audio Video Switch - 8 channel switch. __ Designed by Peter Jakab
8-Digit Code Lock for Appliance Switching - This code lock is useful for appliances requiring exclusive or authorised use by those who know the preset code. if desired, the code can be changed. The circuit doesn’t require additional AND__ Electronics Projects for You