Author Archives: R-B

DC millivolt source

Dilshan’s new project is a DIY millivolt source for simulating precise low-amplitude DC voltages.

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.

DC millivolt source

DC millivolt source

Wireless reset button for your router

Does your router go wonky once every few days and require manual resetting? I know my old router did that quite a bit. Taylor Burley writes about his wireless reset button that will allow you to reset your router and modem from any room with just a click of the button.

Wireless reset button for router

Wireless reset button for your home router

A 555 timer in monostable mode and a hacked door bell were the only things really needed to build this reset. Keep in mind that since I used a powerstrip this device can be adapted to any ac device, within the limits of the relay. I tried to make this project a few different ways before hitting the perfect design. When you hit the button on the doorbell transmiter it sends a signal to the receiver and instead of playing that lovely doorbell tune, the signal that would go to the speaker is rerouted to a transistor that once activated will close pin two of the timer to ground which will then start the monostable pulse. The pulse is 30 secods long, the suggested time for routers and modems, the output of the timer goes to another transistor that will close the relay to ground, once the relay meets ground the coil will charge which will break the contact for the duration of the pulse, then reset after. I ran the ACpower strips live wire through the common pin and normally closed pin on the relay, this way the power is being supplied until the timer is activated. The router and modem are plugged into the power strip. This was the easiest option, instead of cutting into the power supplies for the modem and router. Which, I did a few times. But ended up using the strip for simplicity.

MSP430 powered IR remote control for room automation

Rohit Gupta writes about his MSP430 powered IR remote control that he uses for room automation to control a mosquito repeller and a RGB mood light in his room using a Sony TV remote.

MSP430 based IR remote control

MSP430 based IR remote control

Buzz..Buzzzz..buzzzzzzzz .. That is how a lone mosquito irritates you in the middle of the night trying to convince you that his lullaby is helpful. Insignificant or not, But truly that is the underlying inspiration for this project. The Mosquito repellents have this obnoxious smell that I would not like to sleep in and these loner mosquitoes who just piss me off by buzzing in the ear, you have to choose a lesser evil. Obviously, I turned ON the repellent and in a while it goes off but the smell starts building up and I am too lazy to turn it back OFF, leaving the warmed blanket on a chilly Delhi December Night. The nocturnal dilemma .

So, why not just use a remote to turn it back off and maybe add some other things like Reading Light control, Mood Lighting?

Interesting !!

Having the above in mind I thought of building my own Room Automation and Mood Lighting controller and for this time make it look good and “no mess visible”. I had bought some nice overpriced project enclosures a while back and the bigger one of them would be perfect for the project.

Yet another GPS tracker

Here is another GPS tracker using Arduino that is aimed to assist people suffering from Alzheimer and Dementia by notifying their caretakers about their location. It consists of a GPS module, GSM module, Arduino and batteries all enclosed in a 3D printed case. When the GPS module is not within a user-specified boundary, the device will send a text message alert.

GPS tracker for

GPS tracker to assist people suffering from Alzheimer

DIY GPS navigation using Arduino

This DIY GPS navigation system is built under $25 and uses Arduino with a GPS module and a 320*240 TFT to display the topographical maps stored as BMP files on an SD card.

Based on the combination of TFT module and Arduino UNO fram Banggood and the GPS module from the same supplier I built a basic GPS navigation system that uses the topographical maps of The Netherlands (top25raster). In total there are 304 bmp files on an SD card, so the images are very detailed! In principle any 8 bit bmp map can be used. The maps were obtained from www.kadaster.nl, the software is based upon modules from Adafruit.
Sketch plus explanation are available on Github: middelbh/GPSnavigator.
Enjoy and please inform me about optimisations!

DIY GPS system using Arduino

DIY GPS system using Arduino

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