Welcome to my website!

I am currently working as a software engineer. During my regular work hours, I gather requirements, design systems and of course write a lot of code. In my spare time, I like to work on both software and hardware projects. My blog covers a wide spectrum of topics from software development, computer algorithms to embedded controllers and general electronics.

With a master’s degree in Electrical and Computer Engineering from the University of Wisconsin – Madison, I am interested in software and hardware engineering and system integration.

For more information, you can contact me at kerryw@uwalumni.com (due to the volume of inquires I receive, I may not be able to respond to every single email).

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31 Thoughts on “About”

  • Hello Kerry,

    I am impressed with the clarity of your presentations. You remind me of my favorite student Aaron (originally from China). I will like to keep in touch, if it is OK with you.

    Kind Regards,
    Sudhir Gupta

  • Hi,

    I start to use your lib and I think I find a BUG. When I use your function SPISendReceive() with Dat Buffer Commad more that 16 bytes (for example 36). I get an Error code (-1) in SPIDataTransferStatusDef and the Number of Byte Received attributs take a big Value incorrect like this:

    I can send to you a gdb trace of it .


  • Hello Kerry.

    I watched your speed of light experiment and found it very interesting. I would like to perform one in my home. I have an oscilloscope, but not sure I can build the pulse generator and the photomultiplier myself. Is it possible to purchase them from you? I need 2 or 3 sets.


  • Hi.

    Do you know if I can use a photodiode only for the speed of light experiment? I understand I need a fast rise time.


    • Didn’t see your earlier comments. Anyway, you will need to use a PIN photodiode or avalanche photodiode (APD). That said, if your measurement distance is sufficient large (e.g. a round trip distance of 20 meters or longer), then the rise time requirement is not critical as it will not significantly affect the accuracy of the measurement.

  • Hi Kerry.

    Thanks so much for your answer.

    I am doing an experiment checking some characteristics of the speed of light. for the experiment I need to check the difference in the arrival time in picoseconds of an electromagnetic signal to 2 receivers from as far as possible source.

    I have a strong laser which I can see the rise time on my scope from 3 kilometers using this photodiode:


    the problem is that when I turn on the laser, the rise time is very slow, even from 1 meter. I did not use a pulse generator.

    my questions are:

    1. Can I do my experiment without the pulse generator? If not, do you know which one I can use?
    2. Is this photodiode good for a fast rise time?
    3. Do you know of any way I can receive a specific signal from a radio station (like the “beep beep beep” BBC transmits every hour) and show it on my scope in a nanoseconds accuracy? I tried to connect to the earphone plug, but the audio pulse is too wide and I cannot pinpoint it behind 10 microseconds.

    Thanks a lot, I hope I do not take too much of your time,


    • Hi Israel,

      I did a quick check on the photodiode you used (BPX61), and it’s rise time is only rated as 0.02 us (or 20 ns). It is too slow to capture the rising edge of the pulse from the pulse generator (the rise time is sub nano second). To answer your questions:

      1. You will need to use a pulse generator with a very fast rising edge. You can either build your own (like the one I built) or using a commercial unit that is capable of generating pulses with ideally 100 to 200 ps risetime in order to obtain reasonable accuracy.

      2. As mentioned earlier, this photodiode is too slow.

      3. Not sure what you try to do there, but what you could do is to trigger it on a scope and record the waveform and then analyze it afterwards.

      Hope it helps!

  • Hi Kerry.

    Thanks like always for your response.

    I have another question: how can I measure the wavelength of a light pulse with a scope? can I do it with a photodiode? Do I need a special one? Is it possible to set the scope to trig for a certain wavelength pulse and in this way to pinpoint the exact arrival time of the pulse?


  • Hello

    I found your page about the Amrel PPS-2232. I have a very similar unit, the PPS 18-4D. I am having trouble getting the GPIB interface to work. It receives commands OK, but I cannot read data back from the unit.

    Could you please contact me?


  • Hello sir,

    My name is Vishnu M and I’m from India. I would like to thank you for inspiring me (unknowingly) to create my own project website. This is my favourite personal (hobby) project website on the web. I really love the way you describe your projects and document them with relevant pictures, diagrams and code. The Arduino libraries you created are very helpful and I’m following you on Github. I’m not fond of teardown videos but still I’ve subscribed to your YouTube channel. Also I’ve listed your blog/website in my website’s ‘Favourite Project Websites’ section (hope you don’t mind).

    Thanks. :)

  • Re teardown and information on the HP 5350B microwave counter. Thanks for the excellent information. Is the display brightness adjustable – and how is this done? I cannot find a reference to this in the manuals. The 5350B already has LED’s for illumination but they are not at all bright. is this adjustable in software or hardware? Thank You

    • Hi Mark, I don’t believe the display brightness is adjustable. Also, I don’t think the original light source is LED, I think they are just standard bulbs.

  • Kerry,

    I just wanted to say how much I enjoy your videos. Great content, well organized, and well presented. I appreciate your objective approach to things. There are far too many youtube electronics channels with blatant biases or flat out misinformation, so it was a wonderful surprise when I came across your channel about a year ago.

    It’s funny, I think we have similar taste in test gear- I really like Wavetek gear, too, and I’m very fond of the “brown era” Keithley instruments (though really I like all Keithley stuff- haha). I love being able to read the displays from across the room. I’m in school at the moment, and have assembled a small bench setup in my room with 2 196s, a 175A, a Wavetek 275, Tektronix 2465B, and a Power Designs TW5005T power supply.

    Anyway, just wanted to leave a comment and thank you for taking the time to make your videos. Keep up the great work.


  • Hi Kerry,

    I’d like to thank you for your magnificent videos and all the interesting topics you choose.
    I am a mechanical engineer and have been studying software design and programming on my own. I am new to electronics and hope to learn more and more and never stop.
    I really enjoyed the video on Doppler Microwave Transceiver and it made me think of the the HY-SRF05 ultrasonic distance module which can be used to get distance. I thought it might be interesting to try to change it somehow to use it as a speed sensor!!! could it be done?
    I wish I had your passion and 10% of your equipment.

    best regards

    • Hi Vahid, technically speaking yes. But because sound travels much slower and the relative low power of ultrasonic transceivers, it would be very difficult to measure object moving faster than your typical waling speed using similar method by bouncing sound wave off the object.

      If the object emits sound (e.g. car engine or plane engine, etc.) you can actually calculate the speed of the object passively using Doppler effect via only the difference between the approaching frequency and the departure frequency.

  • Hi Kerry,

    Thank you for the HP8566B documentation!
    I recently bought a HP8566B with the slow bit-slice processor (HP9845A). Of coarse I like to apply a MC68000 upgrade, so also bought a 85660-60245 CPU board, but not sure if other boards need be upgraded, modified or calibrated as well? Aware that the Memory/HP-IB boards will not be necessary and the Instrument-Bus and HP-IB connectors are separated and need brackets. Could you send me photos of these 2 – flatcable/connector/bracket – constructions?

    There actually exists a HP upgrade kit for this, but was unable to obtain the details. So, do you have information which could support my intentions?


  • Kerry,
    Did you get anywhere with honeywell. I contacted a electrical engineer and he stated as I did the honeywell thermostat cannot handle 20 amps. Among other flaws

  • Dear Kerry,

    The library you coded for ad7705 is really useful for one channel. Using single channel the library works perfect.
    Raw data range is between -32768 to 32768 for the input -40mv to 40mV. However the range should have been -20 to 20 mv.

    If you attempt to use both channel then the raw data range is -8000 to 8000 approximately only if other than SPIMODE2. If you choose SPIMODE2 then only one channel works and the one is just replica of it.

    I am a bit confused.
    Anyway thanks for your sharing.

  • just stumbled on your poor man’s source measure unit, this is something I am looking into but have not had time to read most of your info. This may be of interest to you, it is AD Multichannel Source Measurement Unit (SMU) Solution at https://www.analog.com/en/design-center/landing-pages/002/apm/multi-channel-source-measurement-unit-smu-solution.html, you may already know about this but if not check it out. Thanks so much for all you posted on this!

  • Hello Kerry,
    I read your article on the construction of a sweep generator for the BK 4011 with interest. Now I have realized the replica and have questions for you:
    The DAC 0800 does not issue an output signal.
    Why did you connect a pull-up resistor to pin 2? The pin is on ground potential.
    In logarithmic operation, all digital input signals on the DAC 0800 are high.
    The sync pulses are OK.
    Do you have any idea where my mistake could be?

    Kind regards
    Joachim Mischke

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