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  1. D

    Wien bridge oscillator help...

    Just do the slew rate calculation.... Regards, Dana.
  2. D

    XR2006-Sawtooth Amplitude Control

    1) Resistor divider on output (or pot), but then its not buffered. So use a OpAmp follower to buffer. 2) Zener diode (again output unbuffered) : Regards, Dana.
  3. D

    Wien bridge oscillator help...

    Actually the slew rate spec in a 741 datasheet is a "typical" spec at room T and nominal V. So no guarantees that part would not be slew limited at 14.6 Khz. Might be prudent to use a 1 or 5 V / uS part (as its probably also typical spec). Regards, Dana.
  4. D

    Wien bridge oscillator help...

    http://www.learningaboutelectronics.com/Articles/Slew-rate-calculator.php http://www.muzique.com/lab/slew.php https://www.rfwireless-world.com/calculators/Op-Amp-Slew-Rate-Calculator.html Regards, Dana.
  5. D

    ADC Values

    If the ref V for the ADC is 5 volts then Vadc = (N x Vref) / 255 where N is the value read from ADC. https://pijaeducation.com/adc-in-arduino/ Regards, Dana.
  6. D

    problem with IAR code

    Zip file seems to be corrupt.....cannot open it with Winzip. Regards, Dana.
  7. D

    Wien bridge oscillator help...

    For a 5V sine out you are right at the limits of the 741 slew rate : Regards, Dana.
  8. D

    PIR motion sensor audio player

    The sensor has a delay to turn off after it has been triggered : https://electronilab.co/wp-content/uploads/2013/12/HC-SR501.pdf https://www.amazon.com/HC-SR501-Sensor-Infrared-Arduino-Raspberry/dp/B07KBWVJMP http://www.jselectronics.com.my/index.php?ws=showproducts&products_id=1905785...
  9. D

    Fire alarm using a PTC as a sensor.

    Also output of comparator should have a series R to the transistor to limit base current. Current should be limited to ~ Relay coil current / 10. Yiou should also have a snubber or diode clamp to manage L based transients from damaging the transistor. R2 should be ~ 10 x R1, R1, depending on...
  10. D

    Audio Amplifier in Common Emitter Configuration

    Simple class A amp design, some ref material : https://www.electronics-tutorials.ws/amplifier/amp_5.html https://d1.amobbs.com/bbs_upload782111/files_29/ourdev_554203.pdf Regards, Dana.
  11. D

    Need help in ECG circuit and arduino code to read BPM

    I dont see any bypass caps on the board for the LM358 and the IA ? Put your scope on infinite persistence, look at supply rails, and try a combination of a 10 uF or more tantalum in parallel with a .1 uF ceramic, and observe the the pk-pk noise before and after addition of the caps. Remember to...
  12. D

    49" monitor repair help

    There is a number of videos on Youtube fixing monitors. Usually high density high pitch connects as previously mentioned, bad caps ion power supply, burnt components in power supply...... Regards, Dana.
  13. D

    PCB - Manufacturing and Assembly Prototype x 5

    Note you can use a Arduino Nano or an Arduino Uno board to program the Attiny85 (save money) : https://www.instructables.com/How-to-Program-an-Attiny85-From-an-Arduino-Uno/ https://www.arrow.com/en/research-and-events/articles/attiny85-arduino-tutorial...
  14. D

    CMOS Logic input C limitations

    Discussion why hanging large caps at input of CMOS logic not a good idea (Toshiba App Note). https://e2e.ti.com/support/logic-group/logic/f/logic-forum/883065/cmos-logic-input-capacitor-maximum-value https://toshiba.semicon-storage.com/info/application_note_en_20210131_AKX00111.pdf?did=63525...
  15. D

    treble control centre frequency

    I thought one could theoretically produce a desired response (within non linearity considerations) by doing this with N (as necessary) stages : Eg sum the various frequency regions with targeted response for that region and add them all together. So if I wanted a camel hump filter at w/two...
  16. D

    Constant current source

    The OpAmp is the source of signal so it drives R5 and C4. But C4, its "effective" ground end, is R14 since its approaching a V source due to its very low Z. So effectively C4 is from the OpAmp output to ground, hence with internal Zout_opamp, forms a LPF. But we have a path from V on R14...
  17. D

    Constant current source

    Do a sim and test out your thoughts. RC high pass looks like : Regards, Dana.
  18. D

    treble control centre frequency

    Range of 5% to 100% on the pot (two pots ganged) : Regards, Dana.
  19. D

    treble control centre frequency

    Here is the cascade, 4'th order : Regards, Dana.
  20. D

    1960s Chip ID

    Looks like Fairchild logic, TTL and DTL possibly. DTL and TTL was introduced in early 60's. http://www.bitsavers.org/components/fairchild/_dataBooks/ Regards, Dana.
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