Do not skip bypass capacitors

If you are designing some circuits, you probably know or by intuition add bypass capacitors to every IC power rail. Almost everywhere you will find scarce info that you need to place cap as close to IC as possible. In order to get deeper understanding why these caps are needed, sana syed on electro-labs wrote a tutorial about bypass capacitors explaining the meaning of it and what size of capacitor is needed. The main reason why bypass capacitors are used is to filter out high frequency noise and glitches from DC voltage. It can be power supply or DC biasing. If you know fundamental electronics, then its clear that capacitor allows AC to pass while stops DC. So if carefully selected capacitor it passes high frequency noise directly to ground and leaves DC voltage cleaner. It turns out that not any capacitor will do its work as expected. Some calculations may help refine the choice and filter out undesired AC noise or simply pass AC signal without affecting DC part. Continue reading

Detecting power outages with alarm

Probably you have couple appliances that are reliant on constant power supply. It can be anything like fridge, water pump, server, router. If these things are next to you you can react instantly if power supply fails. But what if this happens in remote area. If you have fridge somewhere else and power fails, in time you can get loads of crap. In order to avoid such situations Medhi started Arduino power failure alarm project, where circuit would detect when power fails and send short message to owner so he could take actions immediately and save a day. Alarm device is based on Arduino. In order to send SMS, he used old Nokia3310 phone, which has plenty of info on interfacing using FBUS commands. Next thing here was to detect power failure. This is implemented using Arduino power supply with backup 9V battery. Arduino simply senses incoming voltage from supply adapter and if it fails, then it switches to backup battery. In order to have enough power to switch between supplies there is a large cap that prevents from resetting… Continue reading

The Simplest Ways to Turn Old Hard Drive into Super Cool Hard Drive Clock!

Have a bunch of old unused hard drives and you don’t know what to do about it? Instead of throwing it into the trash bin, you can simply modify it into a cool hard drive clock! Technically, it won’t cost you a dime to do the modification, as you’re going to use the recycled items to build this hard drive clock. By the way, those essential components that you’re needed are: Solid metal case, LED at front panel, Power connector and switch at the back, Power supply +5V and +12V, and A 12V fan. Well, this project is based on PIC18F2320, which is running at 40MHz. The microcontroller can be used to read current time and date from RTC. It will automatically refresh data every hour. Two timers of microcontroller synchronize work of whole device. There are two different timers, which as Timer0 and Timer1. Timer0 is responsible to measure time of full disk revolution and calculate moment for LEDs to turn On/Off. Timer1 is configured as real time clock and is used to scan keyboard, and refresh LCD. By… Continue reading

21st Century Sundial – The Combination of Ancient and Modern!

Although it’s already 21st century, but is nothing wrong to build a sundial, isn’t it? If you think it’s impossible to combine the ancient and modern technologies together, then you should read on this article… As you can see on the above figure, this is the finest combination of the 21st century and ancient time technology! Go figure, what would be the ancient people say, if they found out this incredible 21st century sundial? Yeah, they might be impressed of it! This project is built around an Atmel Attiny24 with crystal for better accuracy. The internal RC oscillator could be calibrated, but the precision can be easily achieved from crystal quartz! The whole project is quite simple, as you’re only need these following components, which as: Micro with Crystal and capacitors, The LASER, The transistor, The servo, and The power supply. The 21st century sundial project should be placed on the open space, especially on the white color wall, as the LASER is mounted on a RC servo and being projected onto the wall by a microcontroller. The microcontroller is… Continue reading

The Huge LED Display Ultrasonic Range Meter

Have you ever thought of building an ultrasonic range meter before? Oh, you think it’s hard to develop this tool, then you should spend a few minutes and read this on… Frankly, ultrasonic range meter is a PIC-based project, where the heart of this stuff is PIC16F873. The ultrasonic signal, where is always received with the reception sensor is amplified by 1,000 times of voltage with the operational amplifier with two stages. It is 100 times at the first stage and 10 times at the next stage! In general, the positive and negative power supply is being used for the operational amplifier, and the circuit will work with the single power supply of +9V. Some of the parts that needed to make this ultrasonic range meter are: Sturdy case: You can make the case with the acrylic board. Variable resistor: It used to revise the error of the display by the change of temperature. Knob: You have to put it on the variable resistor. Sound horn: It is for the decrease the ultrasonic that being reflected at the thing. AC… Continue reading

DIY a Dual Trace Scope By Your Own and Save Enormous of Money!

As we all knew that the currently worldwide economy has been moved in the downward position and most of the countries all around the globe have been seriously affected by this economy crisis. It’s getting hard and harder to earn our living and that’s why you should learn how to save as much of money as you can! However, some of you may think that it’s easier to be said than done… Well, guessed what! Would you believe if you could develop the cheapest dual trace scope with a cost less than $8 per unit? It seems unbelievable but this is the fact! For your information, this submini USB dual trace scope is based on Atmel Tiny45 CPU and it’s a homemade PCB. It has two analog inputs and can supply 5V onto the four pins header on the right. Beside that, one of the inputs can be scaled down with the trim pot. Instead of the low development cost, this dual trace scope’s size is about a credit card and it’s a very cute and compact component as well!… Continue reading