Homemade Circuit Designs Just for You

This site is dedicated to all electronic hobbyists and professionals. Here you can post circuit related queries, have discussions and also publish your own homemade circuit ideas. Get circuits on demand.

Thursday, November 27, 2014

Long Duration Timer Circuit Using Transistors

The articles explains a very simple long duration timer circuit which uses only a couple of transistors for the intended operations.

12V Car Laptop Charger Circuit Using Boost Converter

The post discusses a simple boost converter circuit for charging laptops from a 12V car battery. The idea was requested by one of the avid readers of this blog.

Wednesday, November 26, 2014

Solar Panel Enhancer Using Solar Mirror Concept

In this post we learn a couple of homemade techniques for enhancing a solar panel output performance by many folds.

Monday, November 24, 2014

High Current Transformerless Power Supply Using Dimmer Switch

In this post we discuss an effective and efficient high current capacitive compact power supply using a dimmer switch gadget.

Saturday, November 22, 2014

Transcutaneous Nerve Stimulator Circuit

Transcutaneous electrical nerve stimulation (TENS) is a term typically referred to the use of nonpharmacologic or noninvasive kind of treatment for neutralizing superficial pains.

Friday, November 21, 2014

Boost Charger Circuit for Super Capacitors

 The post explains a simple boost converter circuit which converts a 12V car battery volatge to an elevated 16V for charging a bank of super capacitors. The idea was requested by Miariver.

Self Optimizing Solar PWM Charger Circuit with Buck Converter

The post discusses a simple IC 555 based PWM solar battery charger circuit that automatically sets and adjusts the charging voltage in response to the fading sunlight conditions, and tries to maintain an optimal charging power for the battery, regardless of the sun ray intensities. The attached buck converter ensures an efficient conversion so that the panel is never subjected to stressful conditions. 

Thursday, November 20, 2014

Heart Rate Monitor, Alarm Circuit

The post explores a simple circuit which may be used for monitoring the critical heart rate of a patient (senior citizen), the circuit also includes an alarm for indicating the situation.  The idea was requested by Mr. Raj Kumar Mukherji

Heart Rate Sensor with Processor Circuit

The signal conditioning circuit consists of two identical active low pass filters with a cut-off frequency of about 2.5 Hz. This means the maximum measurable heart rate is about 150 bpm. The operational amplifier IC used in this circuit is MCP602, a dual OpAmp chip from Microchip. It operates at a single power supply and provides rail-to-rail output swing. The filtering is necessary to block any higher frequency noises present in the signal. The gain of each filter stage is set to 101, giving the total amplification of about 10000. A 1 uF capacitor at the input of each stage is required to block the dc component in the signal. The equations for calculating gain and cut-off frequency of the active low pass filter are shown in the circuit diagram. The two stage amplifier/filter provides sufficient gain to boost the weak signal coming from the photo sensor unit and convert it into a pulse. An LED connected at the output blinks every time a heart beat is detected. - See more at: http://embedded-lab.com/blog/?p=1671#sthash.PO5jCRyx.dpuf
The sensing of the heart pulses is basically done by two IR photo diodes one being the transmitter of IR while the other acceptor.

Monday, November 17, 2014

Solar Induction Heater Circuit

In this post we discuss an induction cooker/heater design which may be powered from a solar panel voltage. The idea was requested by Mr. Vamshee
Readers are advised to proceed with the construction of the presented circuits only after understanding the concepts from the core. Not adhering to this can lead to failures and frustrations.