Wiring Schematic Diagram Guide

Simple Crystal Tester Circuit Diagram. Most electronics project working with high frequency utilizes crystal in order to generate frequency as oscillator. It is used instead of coil. Coil can be checked with multi-meter if there is any fault, but checking of crystal completely is difficult. In order to solve this problem a simple project using few components is designed call crystal tester.

This circuit consist two NPN transistors, two diode with few passive component. The crystal under test is combining with transistor T1 which further work as oscillator. The combination of transistor T1, crystal under test and capacitors C1 and C2 is work as colpiitt oscillator. If the testing crystal is good then it works as oscillator with transistor T1. The output of oscillator is rectified and filtered by diode D1 and capacitor C2 respectively and given to base of transistor T2. The signal given to base conduct transistor which further glow the LED connected to the collector through resistor R3. If the testing crystal is faulty then LED1 does not glow.

PARTS LIST
Resistors (all ¼-watt, ± 5% Carbon unless stated otherwise)
R1 = 27 KΩ
R2 = 1 KΩ
R3 = 560 Ω
Capacitors
C1 = 0.001 µF
C2 = 100 pF
C3 = 0.001 µF
C4 = 0.004 µF
Semiconductors
D1, D2 = 1N4148
T1, T2 = BC550C
LED1 = Green
Miscellaneous
SW1 = push to on switch

 
In the last few years, the available range of operating systems for PCs  has increased dramatically. Various free (!) operating systems have been  added to the list, such as BeOS, OpenBSD and Linux. These systems are  also available in different colours and flavours (versions and  distributions). Windows is also no longer simply Windows, because there  are now several different versions (Windows 95, 98, ME, NT, XP, Vista  and 7). Computer users thus have a large variety of options with regard  to the operating system to be used. One problem is that not all hardware  works equally well under the various operating systems, and with regard  to software, compatibility is far from being universal. In other words,  it’s difficult to make a good choice.

Hard Disk Selector Circuit Diagram

Switching from one operating system to another - that’s a risky business, isn’t it? Although this may be a bit of an exaggeration, the safest approach is still to install two different operating systems on the same PC, so you can always easily use the ‘old’ operating system if the new one fails to meet your needs (or suit your taste). A software solution is often used for such a ‘dual system’. A program called a ‘boot manager’ can be used to allow the user to choose, during the start-up process, which hard disk will be used for starting up the computer. Unfortunately, this does not always work flawlessly, and in most cases this boot manager is replaced by the standard boot loader of the operating system when a new operating system is installed.

In many cases, the only remedy is to reinstall the software. The solution presented here does not suffer from this problem. It is a hardware solution that causes the primary and secondary hard disk drives to ‘swap places’ when the computer is started up, if so desired. From the perspective of the computer (and the software running on the computer), it appears as though these two hard disks have actually changed places. This trick is made possible by a feature of the IDE specification called ‘CableSelect’. Every IDE hard disk can be configured to use either Master/Slave or CableSelect. In the latter case, a signal on the IDE cable tells the hard disk whether it is to act as the master or slave device. For this reason, in every IDE cable one lead is interrupted between the connectors for the two disk drives, or the relevant pin is omitted from the connector.

This  causes a low level to be present on the CS pin of one of the drives and  a high level to be present on the CS pin of the other one (at the far  end of the cable). The circuit shown here is connected to the IDE bus of  the motherboard via connector K1. Most of the signals are fed directly  from K1 to the other connectors (K2 and K3). An IDE hard disk is  connected to K2, and a second one is connected to K3. When the computer  is switched on or reset, a pulse will appear on the RESET line of the  IDE interface. This pulse clocks flip-flop IC1a, and depending on the  state of switch S1, the Q output will go either high or low. The state  on the Q output is naturally always the opposite of that on the Q  output. If we assume that the switch is closed during start-up, a low  level will be present on D input of IC1a, so the Q output will be low  following the reset pulse.

This is a Simple Telephone In Use Indicator Circuit Diagram. With this circuit mounted in or near every phone in the house, it will allow users to know if the phone is being used and not to pick up the phone. When a phone is taken off hook, the voltage across the tip and ring terminals drops to 10 volts or less. This will cause the FET (2N4360) to turn on and also turn on the transistor (2N2222). When the transistor turns on it will allow current to flow through the LED and make it light. A blinking LED could be used to make the effect better. 

 

The AVR Stick is a simple data logging device that instantiates itself as an HID keyboard and reports the voltages, along with a ‘timestamp,’ from two pins on an ATtiny85. The device uses open source firmware availabe from Objective Development (http://www.obdev.at/vusb/) called V-USB to implement the USB 1.1 standard. The code that runs the application was based on the EasyLogger example application from Objective development. [Link]

Strip LEDs are available in different colours powered by direct current (DC) source. These LEDs  are available as surface mount devices with current limiting resistors. Usually there are 300 LEDs in a 5-metre strip. The strip can be cut into pieces so that  the bits having three or four LEDs can  be used with 12V DC source. The circuit given here uses the strip LEDs to  make an automatic white LED lighting  source.

The circuit is powered by a capacitor power supply connected to AC mains. Capacitor C1 drops the 230V  AC, which is further rectified by the bridge rectifier module and is made ripple-free by C2. Zener diode (ZD1) provides 12V DC to the comparator circuit. Resistor R1 is important in the  power supply as it provides discharge path to the voltage stored in capacitor C1 after the circuit is unplugged from  mains.

The automatic working of the circuit is based on the light-sensing property of the light-dependent resistor (LDR). Operational amplifier CA3140 (IC1) is used as a comparator with two potential dividers in its inverting and non-inverting inputs. LDR1 and  resistor R3 form one potential divider  that provides a variable voltage at the  inverting input pin 2 of IC1. Second  potential divider comprises resistors  R4 and R5, which provide half of the  supply voltage (6V) to the non-inverting pin 3 of IC1. The output of IC1 depends on voltage level at inverting  input pin 2 of IC1 as explained below.

In daylight, LDR1 has low resistance and the voltage at inverting input (pin 2) of IC1 is more than that of non-inverting input (pin 3). This makes IC1 output low, which drives transistor T1 into cut-off condition and strip LEDs do not glow. However, at night the light incident on LDR1 is low and its resistance is high. The voltage at inverting input of the comparator decreases, making it lower than the voltage at non-inverting input. This makes IC1 output high. Transistor T1 goes into saturation,  thus connecting cathodes of LEDs to  ground. All the LEDs in the strip turn  on and remain that way till morning.

Assemble the circuit on a general-purpose PCB and enclose it in a suit-able shock-proof case. Strip LEDs are available in ribbon-shaped form. Use 5cm bits (two bits) having three  LEDs each. The strip can be cut at supply-contact points. Strip LEDs are arranged on a flexible belt with  double-sided adhesive on the back  side, so it can be glued to any surface.  Connect the LED strip in the circuit  with correct polarity.

EFY note. Since the circuit uses 230V AC, there is a risk of electrical shock. Do not touch or troubleshoot when the circuit is plugged in.Before connecting the circuit to the power supply section, test it using 12V DC from a battery or DC power supply.