Recent content by Platonas

  1. P

    veronica fm transmitter

    Hello people, I would like to comment on the cct a little bit. 1.  Stereo can be added lated by the use of a sepparate stereo generator. 2.  The same can be done about pre-emphasis using a cct from another FM transmitter and adapt it accordingly. 3.  The thing I am worring about is the...
  2. P

    Can Anybody explain How this Transmitter Works?

    As Alun stated, Q1 is an RF amplifier for the antenna, Q2 is the tuned cct. The first coil is mainly used as an antenna impedance match that also shorts to ground the lower frequence range. Hence it must have an inductance greater or equal to that of the other coil of the tuned cct.
  3. P

    Final Year Project For Electronic Egn

    I suggest you do something with a microcontroller.  Some ideas are: - An SMS remote controller (switches on-off remote devices by sending the appropriate SMS message). - A data logger, voltage, temperature or anything else you might need to record over long durations. - A central heating...
  4. P

    Board Design Programs?

    I will sugest 3 different products that look good and are cheap. 1. Proteus (w*w.labcentre.co.uk) 2. CircuitMaker (w*w.circuitmaker.com) and 3. Eagle (w*w.cadsoft.de) Proteus is supposed to be more inclusive since it has a simulation ability. Circuit maker has also simulation abilities but not...
  5. P

    car battery charger

    Certainly current limittation is only achived by the transformer capabilities. A flat battery would absorb high currents at the begining of its charging until the voltage reaches  a level near the set voltage by the pot.  At this level, conduction is not for the full cycle but for a smaller part...
  6. P

    car battery charger

    Hello again, About the cct I posted yesterday.  You made a lot of questions and I am sorry I had not said an important detail. A  transformer of 13-14V a.c. is used.  Then a full wave bridge rectifier is connected to the cct. So, we have d.c. cycles (positive) at he upper part of the cct and the...
  7. P

    car battery charger

    I made in the past a car ttery charger with thyristors.  The cct is simple and works fine. It was modified to work with 24V (two batteries in series) but can be modified back for 12V operation very easyly. Just make R1=1 to 1K2 and zener diode D1 should change to 6v. For 12V operation use the...
  8. P

    tranasistor with amplifying factor 200

    What size of transistor do you need? If it is a normal, small signal transistor, there are many available.  U can use those described in previous post, also have in mind the working voltage, current and power. To add some more u can use: BC547C, BC550C, BC548C, BC239C, BC184, BC237B, ZTX108C.
  9. P

    4W FM Transmitter

    Referring to my previous post.  Yes Audioguru, you was right.  I was reffering to a wrong schematic, I was talking about http://www.electronics-lab.com/projects/rf/001/index.html.  I don't know how do I did such a reference mistake. The transmitter you are talking about (4W with two transistors...
  10. P

    4W FM Transmitter

    Hi, For both of the initial questions. T1 can be 2n2222, 2n2222a, 2n2219, 2n2219a, bsx20 maybe 2n3904 and other simillar transistor, slide variations for the C7 capacitor's value to achive oscillation at the desire frequency. T2 is better to be 2N4427, 2N3866, 2N3924, 2N3553. For the coils use...
  11. P

    HV power supply

    The Crockcroft-Walton is simple to produce high voltages but at very low current values.  The impedance of the cct increases exponentially with the number of stages, hence it is impracticable to be used when you need high current. Anyway, appart from the microwave oven transformer you may try...
  12. P

    4W FM Tx

    I had built the cct many many years ago and worked fine. You must check first the 3 resistors if are of the correct value. R3 & R4 are both 10K. In case you made R4 = 1K then Tr1 will overheat.  Is R5 = 82 Ohms?  You can increase this value up to 120 Ohms without any significant reduction...
See more
Top