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  1. K

    RIAA phono preamp

    There is also the need to properly load the phono cartridge of your turntable for flat response. The Moving Magnet (MM) cartridge may need 47K with 250pF termination. Does the audio preamp have the ability to provide this load? Also, you need to assure you have the proper gain for optimum signal...
  2. K

    POU Hot Water Source (beer brewing)

    Many years ago I did a student 'work-week' for a quartz crystal (oscillator kind) manufacturer. My first task was to measure the resistance of these tiny bead thermistors that were to be placed inside the crystal case. Well, wouldn't you know that the resistance kept changing due to self heating...
  3. K

    Hydrophone amplifier and sampling

    The OP has an interesting project going that I'd like to learn from. In an AudioXpress (April 2007) edition, Dennis Colin had a project that used a couple of LSK389 in parallel whose output was fed to an AD797AN opamp. He claims around a 1nV/sqrt(hz) referred input RMS noise performance. Later...
  4. K

    rc transmitter

    I too was looking for an R/C transmitter-receiver for a small rover. A friend uses one similar to this; https://www.amazon.com/GoolRC-Flysky-Transmitter-Helicopter-Receiver/dp/B00VE3PZ3Y/ref=sr_1_10?keywords=flysky&qid=1568156037&s=gateway&sr=8-10, with good success.
  5. K

    organ foot pedal MIDI controller- switch ideas?

    I've worked on an organ that used a cylindrical magnet in the end of each pedal and a reed switch would close a contact when the pedal was depressed. Here is one idea; http://www.musanim.com/mam/organproject.html
  6. K

    Midi + Solenoid

    Ok, that project/link can help you. The link uses an UNO but you could also use a Teensy but the pin numbers may be different. I haven't used my Teensy yet thus can't guide you in substituting the UNO with a Teensy.
  7. K

    Midi + Solenoid

    Yes, a Teensy can do it. Have a look here; https://learn.adafruit.com/midi-solenoid-drummer/overview
  8. K

    Custom Teensy 3.6 Crystal

    Yes, the series resistance can cause a slow start-up or "sleepy crystal". I found this article helpful, https://www.electronicdesign.com/analog/fundamentals-crystal-oscillator-design
  9. K

    Reading a 1Mhz -15V to Gnd clock

    Where did you see the 250ma current spec? On page 6 I found 25ma.(https://www.nxp.com/docs/en/data-sheet/K66P144M180SF5V2.pdf) Not familiar with the Teensy regarding slew rate control. The simulator is model dependent, so if the part model included all the parasitic elements then it would...
  10. K

    Need help: InternalTemperature lib and bad analogRead value...

    Somebody might be able to help, but first; "Always post complete source code & details to reproduce any issue!"
  11. K

    Reading a 1Mhz -15V to Gnd clock

    I wasn't able to make my circuit simulation malfunction using the pulse width values you gave. So, perhaps I'm not simulating it correctly? I wonder what your scope output does look like using this circuit only with your -15V pulse data. Then, if this test looks OK, connect this output to the...
  12. K

    Reading a 1Mhz -15V to Gnd clock

    I'd be interest to see a 'scope shot of a data stream including your sync. Apparently LTSpice has a way of using a data file to stimulate the circuit so one can see what the output would be with such a signal. Could you get me some samples of data? PeterB
  13. K

    Reading a 1Mhz -15V to Gnd clock

    Before you connect a CD4050, try to see if there is a negative dc level in your output. My data sheet says not to go below 0.5V input. As Paul mentioned its possible to shift the dc point via resistor changes. Hence recommending tighter resistor values. That's one reason I suggested an ac...
  14. K

    Reading a 1Mhz -15V to Gnd clock

    Perhaps you have. How about using an AC coupled circuit with clamping diodes and an emitter follower, like below? You can fiddle with the values to get a good waveform. I use LTSpice for a quick check. Haven't fine tuned it.
  15. K

    Reading a 1Mhz -15V to Gnd clock

    I didn't do any testing, but drew the diagram to provide a proof of concept. Your selection of a high speed opto is better since it is designed to work with 3.3V. The 330 ohm was an arbitrary value I picked. The datasheet you just gave uses 350 ohms for the pull-up resistor of the opto's output...
  16. K

    Reading a 1Mhz -15V to Gnd clock

    That opto is too slow. I was thinking of a 6N137M. You may need to fiddle with the resistor values to get the desired rise/fall times. Also, it is uncertain as to how much delay this circuit produces to make this not work for you. Edit: This circuit will invert your input signal. Will it matter?
  17. K

    Reading a 1Mhz -15V to Gnd clock

    I wonder if a 6N137 optcoupler would work as your level shifter. It may work at 3.6V for Vcc, although the datasheet says 4.5V minimum. It would provide ground loop protection for your keyboard.
  18. K

    Reading voltage from current shunt

    Glad to hear its working for you. Further refinements could include an autoranging circuit to bring the shunt voltage closer to the maximum analog input of the Teensy, but you may not require such a feature.
  19. K

    Reading voltage from current shunt

    What voltage do you measure from either two wires and ground when the battery is charging, or when the equipment is run from battery only? Your planned circuitry will need to compensate for this offset voltage if your run your Teensy DC supply from the same aircraft DC voltage source due to the...
  20. K

    Making a Cuckoo-Clock with Teensy

    I still have one of those clocks.
  21. K

    FFT analysis of AC motor

    You need to isolate the motor voltage or current that you wish to analyse. This can be done via a suitable transformer, or an isolation current to voltage transducer (hall effect device?), along with protection to ensure that the resulting input to the Teensy does not exceed the A/D input...
  22. K

    [posted] Strobe Tuner for Guitar based on Teensy 3.6

    Does your tuner have a means to determine how many cents it's off, or be able to set it to x-cents off? Years ago I worked with an organ technician who had a "home built" organ tuner that showed tuning by LEDs for each 12 notes and cents "error" on a meter marked +50 to -50, as some...
  23. K

    what could cause this behaviour with 4051-muxes?

    Hard to say with no actual hardware (or schematic) in front of me. If all the "ducks" need to be aligned precisely before it works I would expect a timing issue somewhere, or faulty code. Decoupling capacitors required? Better power supply regulation required? Not accurately following the...
  24. K

    Arbitrary waveform object issue

    Thanks Theremingenieur.
  25. K

    Arbitrary waveform object issue

    What values do you recommend?
  26. K

    Arbitrary waveform object issue

    Sorry, ... beginner's oversight. I didn't scroll down far enough, where the pots are read and thus connected.
  27. K

    Arbitrary waveform object issue

    Looks like an interesting project. I don't see where you connect the pots to the Teensy in your code.
  28. K

    <PID_v1.h> myPID.Compute() function in IntervalTimer on Teensy 3.5

    I was dabbling with PID V1 a couple of years ago using an Arduino UNO with a standard 16MHZ clock. My notes said that PID.compute() took 80 usec. The default myPID.SetSampleTime () is 100 millisec. The PID V1 library was designed for the Arduino (UNO) platform, as I understand it. I haven't...
  29. K

    SN74HC165 shift register revisited

    I'm interested in how you made/cut the panel for the switches and the labelling. I often don't get past doing "a proof of concept" because of a lack finishing details and equipment. Thanks. Peter.
  30. K

    Problems with 8x8 RGB LED Matrix

    Also see this for a direct connection to an 8X8 RGB module, https://github.com/marcmerlin/LED-Matrix/
  31. K

    7 segment LED display with Teensy 3.6

    How about the CD4511? https://www.digikey.com/product-detail/en/texas-instruments/CD4511BE/296-2072-5-ND/67341
  32. K

    Teensy 3.5/3.6 and simple headphone hookup

    No, not yet. It may be awhile before I get to an audio teensy project, as I have a number of other projects on the go.
  33. K

    Teensy 3.5/3.6 and simple headphone hookup

    I use this unit for similar reasons for my headphone listening/testing of various audio devices. It has a gain switch for selecting High and Low to cover most situations.
  34. K

    MSGEQ7 maximum output voltage and teensy 3.6

    The datasheet says minimum 3.5V swing, but typically 4V swing, for a 5V DC supply. I'd use a 3.3V power supply and then evaluate what the MSGEQ7 is not doing so well at 3.3V.
  35. K

    Teensyduino 1.41 Released

    Thanks, Paul. I thought that it might have been removed due to some incompatibility with the new Lib, meaning that "NewPing" couldn't be used.
  36. K

    Teensyduino 1.41 Released

    Libs removed: NewPing. Is there a substitute for those wanting a "NewPing" function? I am in the process of building a 2WD Arduino rover with an Ultrasonic sensor. I'm currently planning to use an Arduino UNO (came with the kit) but could upgrade to a Teensy 3.6 in the future since I have one.
  37. K

    Teensy 3.6 connecting a 3.5mm Jack

    I could only find this which is for an Arduino, but you may be able to use your Teensy 3.6 board too. I don't have the changes you would need to make.
  38. K

    Touchscreen MIDI Controller

    Thanks for the link. I'll take a look.
  39. K

    Touchscreen MIDI Controller

    Hmmm.... I may become interested in this project. Our church has an old Johannus OPUS 1100 organ that has a MIDI out only, which no one uses. I've often wondered what that port provides. Maybe just keypresses? Would your project allow reading a MIDI port and tell what is being received from a...
  40. K

    Teensy 3.6 connecting a 3.5mm Jack

    It isn't clear to me what you consider to be "a good idea", as I don't clearly know what this project is connected to. Simply connecting your 3.5 mm jack to an analog input is too simplistic, and not "a good idea" to me. The audio signal must be within 0v and 3.3V, a unipolar signal. Your source...
  41. K

    High sampling rate measurement for weak electrish fish

    Could there not be a DC bias on the probes? I would agree that the right-side diagram of yannick's schematic uses AC coupling to avoid such a DC. The article I linked in a previous post (#48) also use AC coupling.
  42. K

    High sampling rate measurement for weak electrish fish

    Jumping in here, rather late .... I'm not fond of your electrode - Teensy interface. I would prefer using a "instrumentation amplifier" chip. Also, this article (http://www.physiology.org/doi/full/10.1152/jn.00757.2011) may help in your endeavours. It shows a schematic to help with the electrode...
  43. K

    4 channel mono output?

    Thanks. No its not a serious issue, just an observation on my part. It wouldn't significantly change the total current as most of the current is consumed by the IC.
  44. K

    4 channel mono output?

    I'm not a frequent viewer here, but I don't know what a "chamberlain" filter is. I do know about the biquad. Did your stepdad work on vacuum tubes? The resistor values of your opamp circuit reminded me of those days. They could be cut by a factor of 10 - which means the capacitors should be...
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