Saturday, April 13, 2013

FINDING THE BASE and determining NPN or PNP

FINDING THE BASE  and determining NPN or PNP
Get an unknown transistor and test it with a multimeter set to "x10"
Try the 6 combinations and when you have the black probe on a pin and the red probe touches the other pins and the meter swings nearly full scale, you have an NPN transistor. The black probe is BASE
If the red probe touches a pin and the black probe produces a swing on the other two pins, you have a PNP transistor. The red probe is BASE
If the needle swings FULL SCALE or if it swings for more than 2 readings, the transistor is
FAULTY.
 
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Phono Preamplifier Circuit

Simple circuitry, Passive high-frequency equalization
n recent years, following CDs introduction, vinyl recordings are almost disappeared. Nevertheless, a phono preamplifier is still useful for listening old vinyl discs from a well preserved collection. This simple but efficient circuit devised for cheap moving-magnet cartridges, can be used in connection with the audio power amplifiers shown in these web pages, featuring low noise, good RIAA frequency response curve, low distortion and good high frequency transients behavior due to passive equalization in the 1 to 20 KHz range.

Phono Preamplifier Circuit diagram:
Phono Preamplifier Circuit diagram 
Parts:
R1 = 47K
R2 = 100R
R2 = 6.8K
R4 = 68K
R5 = 2.7K-1/2W
R6 = 2.7K-1/2W
R7 = 2.2K
R8 = 39K
C1 = 100uF-25V
C2 = 100uF-25V
C3 = 100uF-25V
C4 = 47nF-63V
C5 = 47nF-63V
D1 = BZX79C18
D2 = BZX79C18
Q1 = BC337
Q2 = BC327
J1 = RCA Jack
IC1 = LM833, Opamp

Notes:
  • R2, R3, R4, R7, R8, C4 & C5 should be low tolerance types.
  • Schematic shows left channel and power supply.
  • For stereo operation R1, R2, R3, R4, R7, R8; J1; C1, C4 & C5 must be doubled.
  • Numbers in parentheses show IC1 right channe
Source :  http://www.ecircuitslab.com/2011/06/phono-preamplifier-circuit.html
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Voltage to current converter with floating load


          The current in the feedback loop depends on the voltage and Ri.
This applications where we need to pass a constant current through a
load and hold it constant despite any changes in load resistance or load
voltage. When the load does not have to be grounded, we simply place
the load in the feedback loop and control both input and load current  from this circuit.
          
This circuit shown in figure voltage to current converter
with floating load. The voltage to current converter can be used in
such applications as low voltage dc and a voltmeters, diode match
finders light emitting diodes (LEDS) and zener diode tester.

         This circuit diagram Figure shows a voltage to current converter in which load resistor RL is
floating (not connected to ground). The input voltage is applied to the
no inverting input terminal and the feedback voltage cross R1 drives the inverting input terminal. This circuit is also called a current series negative feedback amplifier because the feedback voltage across 1 (applied to the inverting terminal) depends on the output current i0 and is in series with the input difference voltage vid.




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Outdoor LED Solar Lights Circuit Schematic

This Outdoor LED Solar Garden Lights venture is a passion circuit of an computerized garden mild the use of a LDR and 6V/5W solar panel. During day time, the internal rechargeable 6 Volt SLA battery receives charging current from the linked sun panel thru polarity safety diode D9 and current restricting resistor R10. If ambient light is commonplace, transistor T1 is reverse biased through IC1 (LM555). Here IC1 is wired as a medium current inverting line forcer, changeed by using an encapsulated light detector (10mm LDR). Multi-turn trimpot P1 sets the detection sensitivity. When ambient gentle dims, transistor T1 turns on to force the white LED string (D1-D8). Now this lamp load on the output of T1 energizes. Resistors R1-R8 limits the running current of the LEDs. When the ambient mild level restores, circuit returns to its idle state and light(s) changeed off by way of the circuit.

Circuit diagram:
Outdoor Garden Solar Lights Circuit Diagram

Assemble the Outdoor Solar Lights circuit on a basic function PCB and enclose the entire meeting in a transparent plastic box. Drill appropriate gaps on the highest of the enclosure to mount the mini sun panel (SP1) and the solarshine sensor (LDR), and in front for fitting power switch (S1) and the sensitivity controller (P1). Fix the battery within the cabinet the use of a double-sided glue tape/pad. Finally, the LDR will have to no longer be mounted to receive direct sunlight. It must be established on the prime of the enclosure, pointing to the sky say southwards. This circuit could be very simple. So and skilled pastimeists can alter/modify the entire circuit as per their very own ideas with none problem (Just are trying a 6V relay with T1 to force extra number of LED strings).


http://www.ecircuitslab.com/2011/10/outdoor-led-solar-lights-circuit.html
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Intelligent Presence Simulator

However effective a home alarm gadget may be, it’s always better if it never goes off, and one of the most straightforward methods to ensure this is to make doable burglars think the premises are occupied. Indeed, until you personal outdated grasps or objects of great worth more probably to attract ‘professional’ burglars, it has to be stated that the majority of burglaries are dedicated by way of ‘petty’ steals who're going to be taking a look greater than the rest for simplicity and can want to interrupt into houses whose occupants are away.

Rather than simply now not occurring holiday – which is also one technique to the problem (!) – we’re going to signify building this sensible presence simulator which ought to position attainable burglars off, although your house is subjected to shut scrutiny. Like all its counterparts, the proposed circuit turns a number of milds on and off when the ambient light falls, however whereas many instruments are content to generate fastened timings, this one works using randomly variable lengths.

Circuit diagram:
 \"intelligent-presence-simulator-circuit-diagramw\"
Intelligent Presence Simulator Circuit Diagram

So whereas different softwares are very quickly caught out just with the support of day-to-day commentary (often from a car) because of their too-perfect regularity, this one is way more credible because of the truth that its running instances are irregular. The circuit could be very easy, as we have now employed a microcontroller – a ‘little’ 12C508 from Microchip, which is greater than sufficient for this type ofn utility. It is primarys powered and makes use of rudimentary voltage regulation by using a zener diode.


A relay is used to keep watch over the gentle(s); though this is less based than a triac solution, it does avoid any interference from the primarys attaining the microcontroller, as an instance, all through thunderstorms. We mustn’t disregard this challenge must work very reliably throughout our absence, no matter happens. The ambient gentle degree is measured by a standard LDR (light established resistor), and the gentleing swaping threshold is regulateable by the use of P1 to suit the traits and placeing of the LDR.

Note that enter GP4 of the PIC12C508 shouldn't be analogue, however its good judgment switching threshold could be very suitable for this kind of use. The LED connected to GP1 point outs the circuit’s operating mode, selected by using flooring or no longer of GP2 or GP3 by implys of override swap S1. So there are three conceivable states: permanently off, completely on, and computerized mode, which is the one typically used. Given the software softwaremed into the 12C508 (‘firmware’) and the need to generate very long prolongs with the intention to arrive at lights instances or an hour or extra, it has been vital to make the MCU operate at a vastly scale backd clock frequency.

PCB Layout:
\"pcb-layout-of-intelligent-presence-sim\"
PCB Layout Of Intelligent Presence Simulator

In that case, a crystal-controlled clock is not appropriate, so the R-C network R5/C3 is used instead. For sure, this kind of clock source is less stable than a crystal, however then in an application like this, that may smartly be what we’re after as a degree of randomness is a design target as an alternative of a drawback. Our recommended PCB shown here takes all the elements for this project apart from after all for S1, S2, and the LDR, so as to need to be positioned on the entrance panel of the case with a objective to sense the ambient mild intensity.

The PCB has been designed for a Finder relay capable of swaping 10 A, which must show ample for lighting your home, except you reside in a replica of the Palace of Versailles. The software to be loaded into the 12C508 is available without cost obtain from the Elektor site as file number 080231-11.zip or from the author’s own web site: www.tavernier-c.com. On completion of the solder work the circuit will have to work instantly and can be checked via swaping to manual mode.

The relay should be launched within the ‘off’ position and energized in the ‘on’ position. Then all that is still is to regulate the day/night threshold via altering potentiometer P1. To do that, which you may either use a selection of patience, or else use a voltmeter – digital or analogue, but the latter will want to be digital as a manner to be high impedance – linked between GP4 and floor. When the sunshine degree below which you need the milding to be allowed to come on is reached, alter P1 to read approximately 1.4 V on the voltmeter.

If this price cannot be executed, because of the characteristics of your LDR, scale back or elevate R8 if necessary to achieve it (LDRs are identified to have quite large manufacturing tolerances). Equipped with this cheaper accent, your personal home of course hasn’t grow to be an impregnable fortress, but as a minimum it ought to seem less horny to burglars than houses which are plunged into darkness for lengthy intervals of time, especially in the center of summer season. (www.tavernier-c.com)

COMPONENTS LIST Resistors
R1 = 1k 500mW
R2 = 4k7
R3 = 560R
R4,R6 = 10k
R5 = 7k5
R 7 = LDR
R8 = 470k to 1 M
P1 = 470k potentiometer
Capacitors
C1 = 470µF 25V
C2 = 10µF 25V
C3 = 1nF5
C4 = 10nF
Semiconductors
D1,D2 = 1N4004
D3 = diode zener 4V7 400 mW
LED1 = LED, purple
D4 = 1N4148
T1 = BC547
IC1 = PIC12C508, programmed, see Downloads
Miscellaneous
RE1 = relay, 10A contact
S1 = 1-pole 3-way rotary swap
F1 = fuse one hundred mA
TR1 = Mains transformer 2x9 V, 1.2 -3 VA
4 PCB terminal blocks, 5 mm lead pitch
5 solder pins 



www.ecircuitslab.com
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