Home Blog  





10 Jun 2015

emon

by dkroeske @ github.com:

A cheap 555 timer chip acting as Schmitt trigger combined with a phototransistor or LDR is taped to the ‘flashing light’ or ‘pulsing magnet’ on the electricity meter. The output of the 555 timer chip is connected to one of the GPIO pins on the Raspberry Pi. A Python script (executing in the background) recording 555 events is calculating actual energy usage [e.g. Watt] every time the 555 is signaling and stores epochs in an SQLite3 database. From this, another Python script (executed from e.g. cron) generates all kinds of energy usage information (e.g. kWh or kWday or whatever). Using Node.js (running on the same Pi) all data is ‘RESTified’ enabling spreading out to the W3. To maintain privacy JSON web tokens are required every time the service is queried. Oh, and there is also a Pimatic plugin available (here)

Emon-server – 555 Timer as power usage sensor – [Link]

7 May 2015

 

dog_repeller

When we hear the word “Ultrasonic” we often refer it to bats and dolphins communication. Technically, “Ultrasonic” applies to sound that is anything above the frequencies of audible sound, and includes anything over 20kHz. Frequencies used for medical diagnostic ultrasound scans extend to 10 MHz and beyond. This dog repellent ultrasonic circuit will chase away angry dogs. It comprises of a 555 timer IC, a speaker/piezoelectric and a little ferrite transformer.

The main part of this circuit is a 555 timer IC. A 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element. Derivatives provide up to four timing circuits in one package. You can use the 555 effectively without understanding the function of each pin in detail. Frequently, the 555 is used in astable mode to generate a continuous series of pulses, but you can also use the 555 to make a one-shot or monostable circuit. The 555 can source or sink 200 mA of output current, and is capable of driving wide range of output devices.

To use this circuit adjust 4k7Ω Resistor at resonance frequency of the piezo transducer for maximum amplitude of the repeller ultrasonic sound. At 11 KHz to 22kHz this can reach a value of 10Vpp and the buzzer is a passive one (without generator).

Note: Ultrasonic frequency must be set with a dog nearby.

Component:

4k7Ω Resistor
10uF Capacitor
10nF Capacitor
1k2Ω Resistor
4k7Ω Potentiometer
Piezo
NC Push Button

Dog Repellent Ultrasonic Circuit 2 – [Link]

25 Feb 2015

1_Sec_to_100_Seconds_Timer_PIC

This project is a timer project and build around popular 555 Timer IC, It can be used for all application required a delay of up to 100 Seconds. Onboard board preset to adjust the required timer duration in range of of 1 to 100 Seconds, Tact switch SW1 to reset the timer and SW2 to start the timer. LED D3 works as power indicator and LED D2 to indicate timer operation.

Load can be connected to CN1 Screw Terminal, Out-put has both the operation normally Open and normally closed. Circuits works on 12V DC and consume approx. 100mA current. Very useful project can be used in various applications like water irrigation system, Kitchen timer etc.

Supply input 12 VDC @ 100 mA
Onboard start and reset tactile switch
Relay output: SPDT relay
Relay specification: 5 A @ 250 VAC
Relay state LED indicator
Preset adjustable range function
Power-On LED indicator
Screw terminal connector for easy relay output connection
Four mounting holes of 3.2 mm each
PCB dimensions 48 mm x 63 mm

1 to 100 Seconds Timer – [Link]

24 Aug 2014

q1kj74bwnrmycys4fxg1

A breakout board for the 555 timer exposing the leads astable or monostable implementation.

Hello, my name is Patrick Grady and I’m a highschool senior in the US. I’m an avid programmer and tinkerer and love anything related to electronics and computers.

This past winter I took a class in Digital Electronics and was introduced to the 555 timer. One of the most common applications of the 555 timer is the astable mode, which is unfortunately rather clunky to build on a breadboard. This 555 breakout board does more than expose the 555’s eight pins: it sets you up to run your 555 timer in astable mode with slots to insert two resistors and a capacitor of your choice. This board eliminates all the wiring for the 555 timer. The 555 Timer Breakout Board Plus will cut out the tedium of setting up the 555 timer and will allow hobbyists to dig straight in to their projects.

As a electronics hobbyist myself, I recognize the usefulness of this simple device, but also acknowledge its relevance is limited to the niche market of hobbyist electronics. If you want this device or think a friend could use it, please contribute to the campaign and buy a 555 timer breakout board!

555 Timer Breakout Board Plus – [Link]


7 Aug 2014

20140406_141901-600x450

Kyle wrote an article detailing his DIY automatic water timer:

Now that I have power and output figured out, I need to work on the control aspect. 555 timers are great for simple applications requiring up to a few minutes of delay. At 10 minutes, the RC values needed would boarder the danger zone of the timer not functioning correctly due to the leakage current of the capacitor and the small charge current of the resistor. I could have cascaded two or more timers together but that would be sloppy so I fell back on my trusty friend – the ATtiny micro controller. This would allow me to make changes as I want without redesigning the board.

[via]

DIY automatic water timer – [Link]

24 Jul 2014

photo

Clap switch/Sound-activated switch designed around op-amp, flip-flop and popular 555 IC. Switch avoids false triggering by using 2-clap sound. Clapping sound is received by a microphone, the microphone changes the sound wave to electrical wave which is further amplified by op-amp.

555 timer IC acts as mono-stable multi-vibrator then flip-flop changes the state of output relay on every two-clap sound. This can be used to turn ON/OFF lights and fans. Circuit activates upon two-clap sound and stays activated until another sound triggers the circuit.

Sound Activated Switch – [Link]

18 Jun 2014

This Photodiode based Alarm can be used to give a warning alarm when someone passes through a protected area. The circuit is kept standby through a laser beam or IR beam focused on to the Photodiode. When the beam path breaks, alarm will be triggered. The circuit uses a PN Photodiode in the reverse bias mode to detect light intensity. In the presence of Laser / IR rays, the Photodiode conducts and provides base bias to T1.

The NPN transistor T1 conducts and takes the reset pin 4 of IC1 to ground potential. IC1 is wired as an Astable oscillator using the components R3, VR1 and C3. The Astable operates only when its reset pin becomes high. When the Laser / IR beam breaks, current through the Photodiode ceases and T1 turns off. The collector voltage of T1 then goes high and enables IC1. The output pulses from IC1 drives the speaker and alarm tone will be generated.

A simple IR transmitter circuit is given which uses Continuous IR rays. The transmitter can emit IR rays up to 5 meters if the IR LEDs are enclosed in black tubes.

555 Photodiode alarm – [Link]

31 May 2014

This Photodiode based Alarm can be used to give a warning alarm when someone passes through a protected area. The circuit is kept standby through a laser beam or IR beam focused on to the Photodiode. When the beam path breaks, alarm will be triggered. The circuit uses a PN Photodiode in the reverse bias mode to detect light intensity. In the presence of Laser / IR rays, the Photodiode conducts and provides base bias to T1.

The NPN transistor T1 conducts and takes the reset pin 4 of IC1 to ground potential. IC1 is wired as an Astable oscillator using the components R3, VR1 and C3. The Astable operates only when its reset pin becomes high. When the Laser / IR beam breaks, current through the Photodiode ceases and T1 turns off. The collector voltage of T1 then goes high and enables IC1. The output pulses from IC1 drives the speaker and alarm tone will be generated.

A simple IR transmitter circuit is given which uses Continuous IR rays. The transmitter can emit IR rays up to 5 meters if the IR LEDs are enclosed in black tubes.

555 Photodiode alarm – [Link]

12 May 2014

Photoswitch_Teardown_7809-500x375

Alan Parekh @ hackedgadgets.com bought a photo-switch on ebay and takes a look inside.  He writes:

I spotted this photoswitch on eBay and had to take a look at the guts (search photoswitch if the link doesn’t work since eBay links go stale after a short time). I now see that the same unit is sold in multiple variations which are 24V and 220V. Not sure I would feel safe with 220 on this thing though. I am curious if the 10 ohm resistor is the only difference between the versions. If someone has one of the other versions leave a comment to let us know what the difference is. These are selling for $3.39 which included free shipping from China to Canada! Hard to believe how tilted the scales are here, I wouldn’t be able to ship this within my city for $3.39. The unit is powered from 12 volts AC or DC, it also switches the same power to the third output wire when activated. The circuit is using a 555 for operation. When the photocell goes from light to complete darkness the relay activates in 3 or 4 seconds. You can view full resolution images here.

eBay Photoswitch Teardown – [Link]

8 Apr 2014

Build this homemade “one-size-fits-most” speed controller for use with your hobby projects. It’s small, it’s flexible, and it’s built with off-the-shelf components around the venerable 555 timer IC.

Dial-a-Speed Motor Controller – [Link]



 
 
 

 

 

 

Search Site | Advertising | Contact Us
Elektrotekno.com | Free Schematics Search Engine | Electronic Kits