Search results

  1. audioguru2

    about mixer

  2. audioguru2

    about electronics eavesdropping devices detector

    Find another NPN microwave transistor that is available in your country. Yes.
  3. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    I recognised the broken English accent to this Japanese site: http://hobby_elec.piclist.com/e_ckt28.htm The IC is really an obsolete module that was found in a junk shop.
  4. audioguru2

    7 segment LED counter

    The CD4040 IC is a binary ripple counter, not a shift register.
  5. audioguru2

    NiMH Battery Pack Charger

    It has a problem with its parts. The schematic has a 5V regulator but the text says an 8V regulator. The current is limited by light bulbs but it doesn't say what voltage or current. I think with a 5V regulator then 3.5V/50mA light bulbs from a series string of Christmas tree bulbs would work...
  6. audioguru2

    Plants wattering watcher

  7. audioguru2

    audioguru fm transmitter

    I made a simple field strength indicator for adjusting the tuning of the output stage. My FM transmitter caused strong RF all over my lab which made measuring its field strength very difficult. The tuning for the output stage was very broad and when tuned for a peak at the center of the FM band...
  8. audioguru2

    85dB

    No. The max continuous RMS power for little 4 inch speakers is only 10W or 20W. What is a "max power" for a speaker? You must say for what duration. A speaker might be able to handle 100W for only a few milli-seconds, but might burn if it plays 20 Watts RMS continuously. Continuous RMS power is...
  9. audioguru2

    85dB

  10. audioguru2

    amplify the power (infrared)

    No, ever since I heard how wonderful FM broadcasts sound, I gave up with the narrow-band, distorted and full-of-interference sound of AM broadcasts.
  11. audioguru2

    amplify the power (infrared)

    This AM modulated IR transmitter circuit should work:
  12. audioguru2

    amplify the power (infrared)

    I think the base of the oscillator should be modulated then it can connect to a common-emitter LED driver transistor. An oscilloscope will show you what the transmitter is doing.
  13. audioguru2

    audioguru fm transmitter

    Don't connect the antenna of your field strength meter to the antenna of the transmitter, and the transmitter's antenna should be about 80cm long. The antenna on the field strength meter should also be about 80cm long and have a fairly low impedance at 100MHz.
  14. audioguru2

    amplify the power (infrared)

    I inverted the black background of your schematic. The value of R7 in your transmitter is so high that the modulator's DC input voltage needs to be -144.5V to bias Q2 into a linear operating region. Also, a very high modulating voltage swing would be needed. If R7 is 39 ohms and the modulating...
  15. audioguru2

    85dB

    A cheap little 4" woofer has a poor sensitivity of 89dB per Watt at 1m. A fairly good 8" woofer has a sensitivity of 92dB. A 12"woofer has a sensitivity of 95dB and so do most tweeters. I don't think I've seen (heard?) an 8 ohm speaker with a sensitivity as poor as 85dB/W/1m.
  16. audioguru2

    Digitally selected outputs for LM317

    Good. I just didn't want somebody to make it with a darlington array then discover that it has a problem with temperature change when the output voltage is set low. An ordinary saturating transistor array won't have a temperature problem.
  17. audioguru2

    Op Amps gain

    Negative feedback is used to reduce the voltage gain, not reduce the output voltage. This circuit would be extremely sensitive to unmodulated light because the opamp's frequency response without negative feedback is flat from DC to only about 2Hz or 3Hz. Of course not, "The output voltage of...
  18. audioguru2

    Digitally selected outputs for LM317

    What about temperature compensation? The turned-on voltage would drop with increasing temperature, wouldn't it?
  19. audioguru2

    Op Amps gain

    Yes. +6dB is twice the voltage, +3dB is twice the power. Yes, it is power gain, but opamps aren't rated for power gain. Opamps use negative feedback to reduce the voltage gain to a usable amount, reduce the distortion and increase the bandwidth. The output voltage of most opamps cannot quite...
  20. audioguru2

    about electronics eavesdropping devices detector

    Hi Desire, Welcome to our forum. ;D Your profile doesn't show where you are in the world. Digikey in the US and Canada has many microwave transistors, but they are all in a surface-mount package.
Top