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  1. audioguru2

    Will this work?

    A 36dB/octave slope is extreme, a 24db/octave one is also very sharp. My point is that the lowpass filter must be made correctly in order for it to work properly. The filter you showed before has a very sloppy response because it was just three cascaded 12dB/octave filters. A crossover frequency...
  2. audioguru2

    0-30 Vdc Stabilized Power Supply

    The resistor R8 has part of P1 in series with it so the total resistance is about 32k ohms. Therefore the cutoff frequency of 32k ohms with C4 is about 50Hz.
  3. audioguru2

    Will this work?

    Hi Mikee, Welcome to our forum. ;D I can't read the parts values in your schematic. It is a huge bitmap file type. It should be saved as a smaller GIF or a PNG file type then attached to your post here to be clear when it is downloaded. In your lowpass filter, you cascaded three Butterworth...
  4. audioguru2

    (HELP) I need a little help

    A transistor or a Mosfet is a one-way valve. The load current affects the voltage. An LED operates with current, not voltage. So a current limiting resistor will have 43V across it. If you want a current of 20mA then 43V/20mA= 2150 ohms. A 2.2K resistor would make 19.5mA flow through the LED...
  5. audioguru2

    Nid Help. Receiver. Op-amp Output.

    The output voltage of a 741 opamp cannot go near its supply voltage. It should be about 10V without a load when the laser shines on Q1. If the laser is too close to Q1 then the input voltage at Va will be too low for a 741 opamp.
  6. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Muffits, Welcome to our forum. ;D R8 and C4 are a filter to remove high frequency noise from the D8 reference voltage circuit. R9 isolates C4 so that D9 can reduce the voltage of the project quickly when current regulation needs it to be reduced. It doesn't matter because the opamps don't...
  7. audioguru2

    rosin flux

    If the rosin turns to smoke when you solder then you might get cancer and your solder joints will be bad because your soldering iron is too hot.
  8. audioguru2

    Digital radar speedometer

    Our Laser Speedometer project doesn't have an accurate quartz crystal nor a calibration pot so I guess it works by majic!
  9. audioguru2

    Surround Sound for car audio

    The discontinued TDA3810 does not make surround sound. It also doesn't make a "spatial-only output". Instead it makes a stereo image wider by cancelling the lowest-level sound that is on both channels, and makes a "psuedo-stereo" from mono by feeding some frequencies to one channel and the...
  10. audioguru2

    Digital radar speedometer

    Our laser speedometer circuit doesn't have a mixer because light frequency is too high for an electronic mixer circuit. Radar uses radio waves and has an electronic mixer diode. Our laser speedometer circuit counts the frequency of the modulation of the reflected laser beam. I assume that the...
  11. audioguru2

    Digital radar speedometer

    I've never seen a radar or laser speedometer circuit before. I am not sure what the Photodiode Circuit does, maybe a very short pulse generator. The same author has about the same circuit using the same ICs in another project of his and he doesn't describe it either...
  12. audioguru2

    Digital radar speedometer

    I don't think our laser speedometer circuit has a mixer. It has a gated counter instead.
  13. audioguru2

    simple FM transmitter.

    When you reply here, click on "Additional Options" then attach your FM transmitter schematics to your reply. If they are already posted at a site then please provide a link to the site. Model aircraft, cars and boats use "servo" assemblies that have a motor, electronic circuit and pot for...
  14. audioguru2

    Comparator Circuit HELP!!!

    Why re-invent the wheel??? Model aircraft, cars and boats use "servos" that have a motor, electronic circuit and a feedback pot inside. They drive the motor with Pulse-Width-Modulation for efficiency, positioning accuracy and high power. The internet is full of information about model servos.
  15. audioguru2

    Digital radar speedometer

    No. Then its max speed detection is a snail's pace. Its filter cuts noise above about 760Hz (for 100mph) or a little higher. Cell phones FM modulate 2.6GHz but FM and 2.6GHz are useless in a laser speedometer. The 2nd oscillator in our project is at a lower frequency than the pulsing modulation...
  16. audioguru2

    rosin flux

    The experts say that barbequed meat and its smoke are carcinogenic due to the very high temp changing the meat and smoke is bad. If you don't have a temperature-controlled soldering iron (mine is a Weller) then the rosin in solder will be well over-cooked too. A soldering iron shouldn't burn the...
  17. audioguru2

    Digital radar speedometer

    Our Laser Speedometer project has two oscillators: 1) A high radio frequency oscillator that pulses the laser at maybe 100MHz. 2) A medium radio frequency oscillator that gates the received pulses that might be doppler shifted in rate. The pulses are gated into the counter for a time period...
  18. audioguru2

    Digital radar speedometer

    Here is Ramsey's Radar Gun's detector diode:
  19. audioguru2

    Digital radar speedometer

    The logic circuits you highlighted are monostable multivibrators that make a pulse of a certain polarity (each circuit has the opposite output polarity of the other) when they are triggered by a short input signal. One pulse resets the counter and the other pulse enables the counter to count for...
  20. audioguru2

    Digital radar speedometer

    You can't calculate the frequency because its timing capacitor's value is much less than stray capacitance of the wiring. 2pF and 10pF are nearly nothing! I don't know how the circuit is supposed to calculate speed.
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