Electronic Mosquito Repeller

 

Mosquito_Repeller

This circuit is built to repel mosquito using high frequency sound. The design is comprised of LM555 timer which provides the pulse generation and precision timing. It is also a stable controller capable of monostable or astable operation. The 74HCT4017BQ device is a Johnson decade counter with 10 decoded outputs. It provides the signal to be fed into the 555 timer which is connected to the output piezo speaker. The piezo speaker generates the sound. The Bipolar Junction Transistors(BJT) BC337 and BC327 acts as the amplifier of the output sound. It forms the push-pull amplifier that is more efficient than a single-ended Class A amplifier.

Electronic Mosquito Repeller – [Link]

Solar self-rechargeable Battery

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This is a prototype model Battery (type C ) for electronic devices. The battery has the ability to be recharged by the sun and don’t need any battery charger. It is necessary for climbers, explorers, soldiers, free camping and general for humans who attempt in areas without infrastructure electricity. The standard can also be applied to other types of batteries and the current technology allows their development with much greater energy capacity.

Specifications of the prototype:

  • Battery 1.2v 700 mAh
  • Solar cell 1.5v 70mA

Solar self-rechargeable Battery – [Link]

Raspberry Pi Compact Camera

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by PiJuice @ instructables.com:

I’m so excited about this new project! A truly compact and portable Raspberry Pi Camera and it’s easy as anything to build!

I first thought about building a Raspberry Pi Camera after seeing the SnapPiCam instructable guide. This is a clever little project, which uses a LiPo battery to power a Raspberry Pi model A. But it got me thinking could I do something even more compact which is even simpler to build?

The real challenge is powering this little baby. Where the SnapPiCam is using a separate battery, converter and charging unit I’ve used the PiJuice. It’s basically an all in one battery module for the Raspberry Pi and it’s an ideal integrated power solution for a DIY Compact Camera.

I’ve also decided to use the Raspberry Pi a+ as it’s the cheapest and smallest available Raspberry Pi so it’ll fit nicely with PiJuice and make this camera supper compact!

Raspberry Pi Compact Camera – [Link]

GPS Tracker for Alzheimer’s Patients

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by LoganP2 @ instructables.com:

The GPS tracking device is composed of a microcontroller, GPS module, cell module, and batteries all housed in a 3D printed case. The microcontroller is programmed to communicate with both the cell module and GPS module. When the GPS module is not within a user-specified boundary, the device will send a text message alert. We made a device that can track people suffering from Alzheimer’s and Dementia could greatly benefit the quality of life of both that person suffering and the caretaker.

GPS Tracker for Alzheimer’s Patients – [Link]

Arduino Fuel Injector Tester

Jeremy Lang wanted to test some fuel injectors for a car he is restoring so he build a tester based on Arduino Pro Mini. Watch the video above to see the tester working and you can find the design files and code on Dropbox.

Arduino Fuel Injector Tester – [Link]

Euroclamp CEM – DIN rail enclosures for every PCB

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Series of enclosures CEMxx in versions for horizontal and vertical PCB placing offers wide possibilities of usage.

17,5 mm/ 22,5mm but also 35mm – in these width is available well-proven series of DIN-rail enclosures Euroclamp CEM17, CEM22 and CEM35, which was introduced to you in our article Gain more space on the DIN rail with housings Euroclamp CEM22.
Enclosures are delivered “complete”, i.e. including a Din rail holder and the top cover. The only, what´s necessary to buy (depending on a target application) are connectors (terminal blocks) labeled as ML25x, i.e. ML252, ML253 and ML254 or PV02 pin headers (PV03, PV04) dedicated for SH02 plug-in connectors (SH03, SH04).

Novelties in our offer are terminal blocks ML253-5-D-LI and ML253-5-S-LI suitable for CEM35 enclosures. From recent types of the ML253 series they differ only in somewhat longer pins (to be soldered into a PCB), what enables them to “lay” directly on a PCB (no need to make a cut-out for a connector).
Enclosureshave a UL 94 V-0 flammability and they are of a grey color RAL7035, other colors upon request. Upon request also imprinting and housings modification are available. Detailed information will provide you datasheets at particular types. Comprehensive overview of Euroclamp connectors and enclosures will provide you the Euroclamp short-form catalogue.


Euroclamp CEM – DIN rail enclosures for every PCB – [Link]

LED DC Voltage Indicator

 

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This design is a type of indicator that is used in voltage reading. It operates as an indicator rather than a meter that drives LED for voltage indication. Voltage thresholds are 1.5, 3, 4.5 and 6V. Above each incremental threshold an additional LED turns on.

LED DC Voltage Indicator – [Link]

RELATED POSTS

Starting with ATTiny13

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by mygeekblog.net:

As any beginner electronics hobbyist I have recently came to conclusion that using Arduino (or even Mega328) for small projects is neither cost-effective or educational (I’ll explain why later).

Another reason for writing this article is that I came across few ATTiny13A-SSU chips @ less than $0.90 each, which is even lower the official retail price, so I just had to buy 5 of them, although I didn’t know at the time whattahellamigointodowithit what is it really capable of.

Starting with ATTiny13 – [Link]

Getting more I/O pins on ATTiny with Shift Registers

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by silentbogo @ instructables.com:

If you previously worked(or currently working) with small 8-bit microcontrollers, like ATTiny or PIC12, you’ve probably encountered a fundamental problem of not having enough GPIO pins for your needs or project requirements.

Upgrading to a larger MCU is only one of the options, but as usual there is an alternative. In this article I will explain how to use shift registers in some common situations in order to expand the I/O capacity of your microcontroller. As an example I will use an ATTiny13A and a 74HC595 shift register.

Getting more I/O pins on ATTiny with Shift Registers – [Link]

Low cost DC millivolt source

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Dilshan Jayakody has published a new project, a DC millivolt source:

DC millivolt sources are often used for thermocouple simulations, DMM, ADC and analog circuit calibrations and fault findings, etc. Most of the DC millivolt circuits are based on expensive (and sometimes hard to find) operation amplifier like OP7, LT1077, etc. In this article we introduce low cost DC millivolt source based on commonly available LM308 precision operational amplifier, ICL8069 low voltage reference and 78L05 voltage regulator ICs. This millivolt source is design to obtain 200mV – 700mV DC output with 100Ω impedance. At the time of writing we spend Rs.800.00 (LKR) to complete this project.

Low cost DC millivolt source – [Link]