Circuit Electronics

small Metronome using 2N3904

noreply@blogger.com (tom) — Wed, 02 Sep 2009 17:06:00 +0000

http://www.elecfree.com/electronic/small-metronome-using-2n3904/

Infrared Intruder Alarm

noreply@blogger.com (tom) — Sun, 30 Aug 2009 17:03:00 +0000

This the circuit warns the trespasser infrared system or Infrared Intruder Alarm circuit that interesting. By when there is a person passes or cut the light infrared.

http://www.elecfree.com/electronic/infrared-intruder-alarm/

Two Tone Alarm with IC LM3900

noreply@blogger.com (tom) — Mon, 24 Aug 2009 17:46:00 +0000

http://www.elecfree.com/electronic/two-tone-alarm-with-ic-lm3900/

Low pass filter circuit 10KHz using uA741

noreply@blogger.com (tom) — Sun, 23 Aug 2009 13:37:00 +0000

http://www.elecfree.com/electronic/low-pass-filter-circuit-10khz-using-ua741/

Small IC Amplifier 2 watt using LM380 | Circuit Project Electronic

noreply@blogger.com (tom) — Mon, 17 Aug 2009 15:15:00 +0000

Small IC Amplifier 2 watt using LM380 | Circuit Project Electronic

Compares with sound level tool | Circuit Project Electronic

noreply@blogger.com (tom) — Fri, 07 Aug 2009 14:45:00 +0000

Compares with sound level tool | Circuit Project Electronic

Low impedance mini amplifier | Circuit Project Electronic

noreply@blogger.com (tom) — Sat, 01 Aug 2009 18:42:00 +0000

Low impedance mini amplifier Circuit
This circuit can apply to signal sound source that has low impedance , such as from 4-16 ohm size loudspeakers or telephone earphone that use to replace

Unused 8051 pin gets assignment

noreply@blogger.com (tom) — Mon, 27 Oct 2008 07:10:00 +0000

In an 8051-based system without external program memory, the program-store enable (PSEN) pin is useless. However, you can indirectly control this pin using software. To do so, you execute the move-constant- (MOVC-) instruction-implementing table look-up. By accessing locations in external program memory (which is actually nonexistent), you can produce pulses on the PSEN line without disturbing program flow. Although you need a register for storing output data, you don’t have to install a decoder.
source:http://edn.com/archives/1996/010496/01di7.htm

A serial to parallel converter using the AT89C2051

noreply@blogger.com (tom) — Mon, 27 Oct 2008 06:55:00 +0000

The example program included with the PG2051 evaluation kit is a basic serial to parallel converter written in 8051 assembler. This is probably a good example of the uses to which an AT89C2051 can be put - it would be hard to get a serial to parallel converter much simpler than the single 20 pin IC in this circuit. The program is meant to serve as a useful example of 8051 serial routines and other programming, whether or not you actually need a serial to parallel converter.
Source: http://airborn.com.au/serial/sertopar.html

Accelerometer Schematic

noreply@blogger.com (tom) — Sat, 25 Oct 2008 16:12:00 +0000

Below is a rough schematic of the layout of the accelerometer PC board looking from the component side. The microcontroller is an Atmel AT89S8252, an 8051 clone. This microcontroller is in-circuit programmable using an SPI interface. The SPI pins are also used to drive the MMC. To permit the dual use there is a jumper block (located below the 74AHC244, marked "P" and "R") that allows the pins to be connected for programming (P) or running the code (R).
Source:http://www.randomuseless.info/accelerometer/schematic/schematic.html

Combine two 8-bit outputs to make one 16-bit DAC

noreply@blogger.com (tom) — Sat, 25 Oct 2008 16:11:00 +0000

Inexpensive, 16-bit, monolithic DACs can serve almost all applications. However, some applications require unconventional approaches. This Design Idea design concerns circuitry I recently designed for a tunable-diode laser spectrometer for a Mars-exploration application. The control circuitry included two 16-bit DACs that interface to the radiation-hardened, 8051-variant 69RH051A microcontroller.
Source:http://www.edn.com/article/CA454640.html

MIDI Drum Machine Project

noreply@blogger.com (tom) — Sat, 25 Oct 2008 16:08:00 +0000

The MIDI Drum Machine began in the Fall of 1991 as a project for a microprocessor system design course, shortly after I wrote PAULMON1, the 8051 monitor/debugger. A friend, Rod Seely, both a musician and electronics hobbiest suggested I design something using the Musical Instrument Device Interface, MIDI, that would be COOL and would work together with his collection of MIDI keyboards and synthesizers. Of course, I wanted to build something that could end up as a finished commercial product.
Source :http://www.pjrc.com/tech/midi-drums/drum-intro.html

Low-Cost Anemometer Fights Dust

noreply@blogger.com (tom) — Thu, 26 Jun 2008 18:33:00 +0000

This application note describes a low-cost circuit that can detect when a chassis fan filter has become clogged with dust. It does this by using a temperature sensor to determine the rate of cooling of a transistor in the air path of the cooling fan, thereby implementing a simple thermal anemometer.

source: http://pdfserv.maxim-ic.com/en/an/AN844.pdf

LX1970 VISIBLE LIGHT SENSOR

noreply@blogger.com (tom) — Thu, 26 Jun 2008 18:29:00 +0000

The LX1970 light sensor can be used in conjunction with an LCD Front or Back Light Controller such as the LX1992 for LEDs or the LX1689 for CCFLs. This application note describes how to design in the LX1970.

Source: http://www.microsemi.com/micnotes/1403.pdf

AM portable radio receiver by ZN414 IC

noreply@blogger.com (tom) — Sat, 21 Jun 2008 14:14:00 +0000

An AM portable radio receiver made from the ZN414 IC. The ZN414 ic has now been replaced by the MK484 which is identical in performance and pinout.

Read More

Micro Power AM Broadcast Transmitter

noreply@blogger.com (tom) — Sat, 21 Jun 2008 14:11:00 +0000

In this circuit, a 74HC14 hex Schmitt trigger inverter is used as a square wave oscillator to drive a small signal transistor in a class C amplifier configuration. The oscillator frequency can be either fixed by a crystal or made adjustable (VFO) with a capacitor/resistor combination. A 100pF capacitor is used in place of the crystal for VFO operation. Amplitude modulation is accomplished with a second transistor that controls the DC voltage to the output stage.

Read more

LM3647 Reference Design

noreply@blogger.com (tom) — Mon, 17 Mar 2008 09:43:00 +0000

The LM3647 provides a single-chip charge management solution for Nickel Cadmium, Nickel Metal Hydride and Lithium-Ion cells. The device handles the entire charging process from rejuvenating deeply discharged cells to providing a number of charge termination and maintenance options. The LM3647 Demo Board allows users to create a battery charging solution with little effort.

Link : http://www.national.com/an/AN/AN-1165.pdf

7.2 Volt Field Charger

noreply@blogger.com (tom) — Mon, 17 Mar 2008 09:41:00 +0000

The unit is novel as it’s display graph shows you the time the battery has been charging in 2 minute intervals up to 16 minutes when finished.... read more

Self-heated transistor digitizes airflow

noreply@blogger.com (tom) — Tue, 11 Mar 2008 03:39:00 +0000

A sensitive and reliable way to measure airflow is to exploit the predictable relationship between airspeed and the heat dissipated by a sensor exposed to the flow while being held at a constant temperature differential above ambient. The power required to maintain the elevated sensor temperature is proportional to the square root of the airspeed (King's law). The popular hot-wire anemometer uses this principle, but suffers from the disadvantage of using a relatively fragile airflow sensor, a thin metallic filament.

Link source: http://www.edn.com/archives/1996/031496/06di3.htm
Thank : www.next.gr

Transistor and FVCs make linear anemometer

noreply@blogger.com (tom) — Tue, 11 Mar 2008 03:37:00 +0000

A previous Design Idea presented a simple flow-to-frequency transducer that easily fits into mP-based measurement systems (Reference 1). You can accumulate and linearize its frequency output by using software without the need for ancillary circuitry. In other applications, however, you might prefer a linearized analog output.

Link source : http://www.edn.com/archives/1996/092696/20di4.htm
Thank www.next.gr

12-bit converter upgrades µC's ADC

noreply@blogger.com (tom) — Wed, 13 Feb 2008 23:19:00 +0000

The simple circuit in Fig 1 and an accompanying software routine let you easily substitute a multichannel 12-bit ADC for the 8-bit ADC internal to the 87C752 µC. A single assembly can then implement both the low- and high-performance version of a system. A socket lets you plug in the external ADC when you need it; otherwise, you plug in the network of 10 100V resistors. At power-up, the µC executes a routine that looks for the external converter.

Source Link : http://www.edn.com/archives/1994/070794/14di5.htm

18-bit ADC uses PC's serial port

noreply@blogger.com (tom) — Wed, 13 Feb 2008 23:17:00 +0000

A PC usually requires a plug-in ADC card to process analog signals. However, with the circuitry in Figure 1, a PC can communicate with an 18-bit ADC through its serial port. The port provides both positive and negative power supplies as well as control signals. IC1 is an 18-bit MAX132 ADC with a serial interface. It requires three input control signals, , DIN, and SCLK, and emits serial data, DOUT, and EOC (end-of-conversion) signals.

Source Link : http://www.edn.com/article/CA159691.html

2-channel ADC tags its own output

noreply@blogger.com (tom) — Wed, 13 Feb 2008 23:16:00 +0000

The circuit in Fig 1 shows a simple way to operate a 1-MHz, 12-bit ADC (IC1) in DMA mode while alternating between its two analog-input channels. The converter operates continuously, driven by the 1-MHz clock on the S/H input. Tying RD and CS low ensures that data are always present on the ADC's output bus. The outputs of the 74HC74 flip-flop, IC2, change state on the rising edge of the end-of-conversion (EOC) signal.

Source Link : http://www.edn.com/archives/1994/042894/09di4.htm

4-bit µP's A/D converter decodes keypad's inputs

noreply@blogger.com (tom) — Wed, 13 Feb 2008 23:13:00 +0000

Fig 1 shows a Mitsubishi M50927-XXXSP/FP 4-bit microcontroller decoding a 4×4 keypad using only four digital I/O lines instead of eight. Saving four of a 4-bit µC's precious I/O lines couild be significant. The 4-bit µC's ADC provides the key to the savings. The µC's output lines, F1 through F4, energize the keypad's column lines one at a time via 74HC4049 buffer/ driver. If a user presses a key, the µC's ADC reads an analog voltage coresponding to the row of the pressed key.

Link Source:http://www.edn.com/archives/1994/101394/21di6.htm

DPP adds versatility to VFC

noreply@blogger.com (tom) — Fri, 08 Feb 2008 07:27:00 +0000

The basic VFC (voltage-to-frequency converter) in Figure 1 comprises an integrator (IC1) and a Schmitt-trigger circuit (IC2). The integrator converts the dc input voltage, VIN, to a linear voltage ramp, and the Schmitt trigger sets the limits of the integrator's output voltage. Feedback around both circuits provides the condition for oscillation. The DPP (digitally programmable potentiometer) in Figure 2 adds programmable limits to the Schmitt trigger and adds two powerful features to the VFC.

Source: http://www.edn.com/article/CA257049.html