Archive for category: Control circuits

Electronic Keypad

Control circuits | By: Diagram mania

Circuit : Ron J Email Ron Description The IC is a quad 2 input “AND” gate, a CMOS 4081. These gates only produce a HIGH output, when BOTH the inputs are HIGH. When the key wired to ‘E’ is pressed, current through R1 and D1 switchs Q5 on.The relay energises; and Q5 is ‘latched on’ […]

Switch De-Bouncer Circuit

Control circuits | By: Diagram mania

Circuit : Andy Collinson Email me Description This circuit will remove the transient spikes and contact bounces from a non-latching push button switch. Notes: Using a 555 timer as a monostable circuit, it is easy to build a good switch debouncer circuit. There are many circuits for SPDT debouncing, but not many for a normally […]

Electronic Doorbell with Counter

Control circuits | By: Diagram mania

Circuit : Andy Collinson Email me Description This circuit uses a synthesized sound chip from Holtek, the HT-2811. This reproduces the sound of a “ding-dong” chiming doorbell. Additionally, the circuit includes a CMOS 4026 counter display driver IC to count your visitors. Circuit Notes: The Holtek HT-2811 is available from Maplin electronics in the UK, […]

Water Activated Relay

Control circuits | By: Diagram mania

Circuit : Marin Lukas, Croatia Email: marin.lukas@zg.hinet.hr Description Notes (English follows) : Ovaj sklop je projektiran da ukljuci relej kada se na knotaktima pojavi voda.Tranzistor T1 moze biti zamijenjen s 2N2222A.Tranzistor T2 mora biti BC108. Na kolektor tranistora T1 osim releja mogu biti spojeni signal injektor, LE dioda, zarulja i ostali signalizacijski elementi. In his […]

Triac Based Light Controller

Control circuits | By: Diagram mania

Circuit :Matthew Hewson Email: matthew.hewson@ntlworld.com Description This project is intended for controlling mains powered disco lighting, although there are many other possible uses for controlling almost any mains appliance. It will control five seperate channels at up to 3 Amp per channel. This could be increased by designing another PCB with wider tracks than the […]

Four-Digit Keypad-Operated Switch

Control circuits | By: Diagram mania

Circuit : Ron J Email Ron Description This is a universal version of the Four-Digit Alarm Keypad. I’ve modified 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 […]

Keypad-Operated Switch No.2

Control circuits | By: Diagram mania

Circuit : Ron J Email Ron Description This is a simplified version of the Universal Keypad-Operated Switch. I have modified the design to reduce the complexity of the circuit – and the number of components required. As a result – the code is somewhat less secure. However, there should be lots of situations where it […]

Electronic Door Release

Control circuits | By: Diagram mania

Circuit : Ron J Email Ron Description This circuit is designed to operate an electrical door-release mechanism – but it will have other applications. Enter the four-digit code of your choice – and the relay will energize for the period of time set by C4 & R4. Use the relay contacts to power the release […]

IR Remote Control Extender Mark 2

Control circuits | By: Diagram mania

Circuit : Andy Collinson Email me Description: This is an improved IR remote control extender circuit. It has high noise immunity, is resistant to ambient and reflected light and has an increased range from remote control to the extender circuit of about 7 meters. It should work with any domestic apparatus that use 36-38kHz for […]

IR Remote Control Extender Mark 3

Control circuits | By: Diagram mania

Circuit : Daniel Pozzi – Argentina Description This Mark3 version of the Infra Red extender is a special version designed to control appliances that use high frequency modulated IR remote controls. Notes IR appliances use pulses (control signals) sent over a modulated IR carrier wave. The carrier wave may be modulated at various frequencies, 36-38KHz […]