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Circuit Ideas

TWOVOLT is an educational site of electronics Projects, Schematics and circuits for various application like Audio, Video, Motor Controllers, Power supplies, Remote controls, and Micro controllers. Effectively web site is personal efforts to build a collection of E-Circuits. TWOVOLT is resource for beginners, hobbyists, engineers, inventors and consultants. This site exists for the purpose of promoting the hobby of DIY Electronics. All project documentation presented on this site is free for personal non-commercial use.

Circuit of the Day
Step Up DC-DC Converter

Project has been designed around Texas Instrument’s LM2623 IC, The LM2623 is a high efficiency, general purpose step-up DC-DC switching regulator for battery powered and low input voltage systems. It accepts an input voltage between 2.4V to 12V volts and coverts it into 5V DC. Efficiencies up to 90% are achievable with the LM2623.





LPT ( Printer Port) Opto-Isolated Board for Mach3, CNC & Routers Softwares wihc works on LPT port

This board  is an Isolated Parallel Port Breakout Board designed specifically for Hobby CNC/Routers, It is compatible with a variety of Parallel Port driven CNC Software. All inputs and outputs port pins are optically isolated to protect PC from potential damage from electro-magnetic noise, high voltages or short circuits.


Voice Record/Playback Module Schemetic

Project   has been designed around Win bond’s ISD1616 IC (SMD) IC, which is fully integrated, single-chip, single massage voice record and playback device ideally project suited to a variety of electronics systems. Massages are stored in flash memories made in unique Multilevel Storage Technology (MLS). Therefore, voice or audio data are stored directly into the memory in their natural form without any compressions alike digital approach, providing high-quality, solid-state audio reproduction. Project provides high quality audio recording and simple operations.  Massage duration is user selectable in ranges from 10 to 20 Seconds depending on the sampling rates from 4 KHz to 12 KHz adjustable via on board potentiometer (preset), giving the users greater flexibility in duration versus recording quality. Massage recording and playback is easy using on board tact switches. This project can be used in variety of application like, Interactive Games and booths, Light and  sound shows, gaming machines, toys, robots, animatronics, lifts/escalators, warning systems, security systems, audio guide, home appliances. Project work on 5V DC @ 100mA. It consumes minimal current in standby mode typical 1uA to 100ua (Without power LED). The device enters into standby mode automatically once an operation is completed for power saving purposes.

Testing the Project,
Connect the 8 ohms 0.5W speaker to LS1 (SPK), apply 5V DC to CN1, and make sure polarity is correct otherwise it can damage the IC. CN2 (AUD) is current drive output to connect the project with external audio amplifier. 
Record A Message
The device starts recording whenever REC switch pressed or recording pin of IC pulled HIGH to LOW and stays at LOW. Recording stops when the recording switch released or the signal on ICs pin returns to HIGH.  The device starts recording from the beginning of the memory when REC transits from HIGH to LOW and stays at LOW. A record cycle is completed when REC is pulled to HIGH or entire memory is filled up. Then an End-of-Message (EOM) marker is written at the end of message, enabling a subsequent Playback cycle to terminate appropriately. Hence, the device automatically enters into standby mode. REC takes precedence over any playback operations. If REC is pulled LOW during a playback cycle, the playback immediately halts and recording starts from the beginning of the memory. The REC pin has an internal pull-up device
Playing the recorded message
Edge-trigger Playback: A playback operation starts when switch (SW2) PLAYE pressed or PLAYE pin of IC detects a LOW going signal exceeding the specified denounced time
Level-trigger Playback: A playback operation begins when switch (SW3) PLAYL is pressed and playback stops when switch is released. PLAYL pin of the IC detects a LOW going signal and remains at LOW. Playback stops when the signal returns to HIGH
The ISD1616 IC provides record/playback duration from 10.6 seconds to 32 seconds. Sampling rate and duration are determined by on board 220K Ohms PR1 potentiometer connected to the Rosc pin.
Sample Rate Rosc. PR1 Potentiometer Duration
12Khz 60K Ohms 10.6 Seconds
8Khz 80K Ohms 16 Seconds
6.4Khz 100K Ohms 20 Seconds
5.3Khz 120K Ohms 24 Seconds
4Khz 160K Ohms 32 Seconds

D1 (Green LED)
The D1 Green LED goes on during recording, the output pin of IC provides an active-LOW signal during recording, which is used to turn on a D1 (Green LED) as a “record-in-progress” indicator. However, during playback, the D1 LED blinks a few times per second to indicate a “playback-in-progress” operation. It returns to an OFF state when operation stops.
D2 work as power indicator, it is in on state during power is on.





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