Posts Tagged ‘bc550’

Class A Buffer preamplifier by BC550

A unit which is often very useful, if we need to isolate, in sound circuits, two stage between them. Then we can use this circuit which has an amplified unit, which gain X1, we do not use total negative feedback, only local, with the result that distortion remains at a very low level. Matching must be done with great care to the types of transistors, resistor between them. There must also be thermal union between the transistors, as well as the diodes LED D1-2 with the transistor Q5 and Q2 respectively.

Part List

R1= 560 ohms C1-2= 100uF 25V Q2-4= BC560C
R2= 47Kohms C3-4= 47uF 25V Q3-5= BC550C
R3= 2.2Kohms C6= 1nF 63V ΜΚΤ Q6= BC560C
R4-7= 1Kohms C7-8= 100nF 63V ΜΚΤ Q7= BC550C
R5-6-10= 100ohms C9-10= 100nF 63V ΜΚΤ J1= 10pin Connector
R8-9= 47ohms D1-2= LED RED 5mm
R11-12= 10ohms Q1= BF 245C All Resistors is 1/4W 1%

Related Links
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Tone Control Mono by Transister C945x5

Read More Source:

http://users.otenet.gr/~athsam/class_a_buffer_amplifier.htm

Thank you.

High Temperature ALARM by BC550

The circuit is small regulatorof temperature, us warns for the increase of temperature. The control of temperature becomes from the thermistor TH1, that is negative factor. His resistance is altered between in the 10K in temperature 25° C and roughly in the 1K in their 94° C. The trimmer TR1 regulates the precise temperature in which the Q1-2, connected as darlington, conduct, making him relay K1 close also the buzzer BZ, sound. The alarm is activated when the temperature becomes bigger than predetermining. The thermistor it should he is placed far from the remainder circuit, in order that this is not in danger from the temperature. The supply of circuit becomes from battery 9V, but if he is placed in constant place, then we can him supply with one power supply . In the contacts of relay we can connect what load we want, as a lamb, other circuit k.a. Also can is added a LED, if we want to have also optical clue of excitation. The regulation becomes sinking him thermistor TH1, in water which we know the temperature of (the contacts should are well insulate so that do not have short-circuit) and regulating him trimmer, until excited the circuit. The cable that we connect the circuit with the TH1, should be plate.

Related Links
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High impedance DC Voltmeter by IC CA3130
Light Sensitive Switch with LDR + 2N2926
Peak Level Indicator by IC LM723
AC Line testing circuit.
Car Temperature Gauge by IC CA3162 + CA3161

Read More Source:

http://users.otenet.gr/~athsam/high_temperature_alarm.htm