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Frank Milburn's Blog

77 posts
The Tin Man is now mechanically and electrically complete.   Printed Parts   I didn't take any photographs during assembly but it was straightforward.  The front and sectional view from the back below shows the parts minus the electronics.   Here are my comments on the outcome: Appearance:  The appearance differs from the model, at least to me.  As printed, he looks thinner and the gap between the eyes and the shell is more prominent. Print Quality:  A ...
Time for more silliness with the Tin Man.  I have been thinking about what kind of voice he should have and spotted the Velleman Voice Changer Kit for $11.   I know it says Whadda on the box but inside the PCB and the instruction sheet says Velleman.   The main IC is a Holtec HT8950 and the passives are arranged pretty much the same as the Holtec datasheet.  There are buttons for vibrato, pitch adjustment, and the "robot" voice.  There is also an LM386N to amplify ...
Jameco has these National Semiconductor NSA1166 7-segment 6-digit bubble displays and I bought a couple to distract me from what I should be doing.   They are very simple to drive as each segment has its own pin that is driven high and each digit has a pin to act as the cathode.  I plan to write my own driver but like everything these days, there is an Arduino library that I am using at the moment.  It might make an interesting display for use with my milliohm meter project whi ...
Last week I started a series of blogs on making the Tin Man from the 1939 movie The Wizard of Oz.  The progress towards completion has been leisurely but this week's update features the first 3D print and code to add speech and smoothed movement to the eyes.  I also showed the Tin Man to Bender who does not seem happy about a new robot in the house.   As a reminder, this is what he will ultimately look like.  I hope.     Printing the Shell of the Head   ...
I've decided to make an animatronic Tin Man loosely based on the 1939 movie The Wizard of Oz for no other reason than I've wanted to for some time.  It seems like it would make a good design exercise.  It would also be someone that Bender could talk to when I am away from the house.  Since the Tin Man has no heart, it seems like a good Halloween project also.  Next to the flying monkeys, he is the scariest thing in the movie.  After all, he is a heartless robot with an a ...
In a recent element14 Essentials on Static Control, shabaz said this:  "A 2N3819 + meter or LED makes a nice simple charge detector too : )"   So, I thought I would try it.  I don't have a 2N3819 but I do have a J112 N-channel JFET.  The circuit is shown below: Power is supplied by a bench power supply set to 3V current limited to 10mA.  The "antenna" is a 5-inch long piece of wire.   So how does it work?  A JFET has extremely high input impedance - hardly ...
fmilburn

Robot Summer Camp 2021

Posted by fmilburn Top Member Jul 31, 2021
This is the 5th year I have held Robot Summer Camp for my grandchildren and there were 2 full-time campers and 1 part-time.  They don't really camp, but one has to sleep on the couch :-).    The purpose of Robot Summer Camp is to have some fun and give the kids some extra exposure to science, making stuff, and the outdoors.  We go for a walk every day, read for at least 30 minutes, build something, and do things with science or electronics/programming.  This year in th ...
fmilburn

Been There, Done That

Posted by fmilburn Top Member Mar 5, 2021
Been There, Done That, Got the T-shirt Next week I get the vaccine   Thanks danzima and tariq.ahmad ...
EDIT  2 Feb 2021:  Added explanation for poor matching of motors   I have an ongoing project to develop a robot which will use a Raspberry Pi for the main brain and I2C communication with a microcontroller for real time activities such as PID control of motor speed.  Links are given at the bottom of this post describing the implementation of I2C communication between a Raspberry Pi and Arduino, and PID (only proportional and integral are used) motor control on an Arduino. ...
I have what seems to be a continuously ongoing project to measure low resistances with milliohm precision.  The latest version had an inexpensive voltmeter that used the Microchip MCP3421 in the display.  The chip costs $2.39 in small quantities from Newark and several were ordered with the idea of installing it directly on the milliohm meter PCB.  One was soldered to a SOT-23-6 DIP adapter for testing with an Arduino MKR1000. The MCP3421 is an 18-bit delta-sigma ADC in a SOT-2 ...
Recently W2AEW, one of my favorite YouTube bloggers, made a video on the Wilson Current Mirror and the Early Effect in Bipolar Transistors.  He explains things clearly without any fluff so go check it out.  I always understand and remember things better if I try them myself so I set a circuit this evening and documented it here for those interested.  My design will be for 5 mA current.   Schematic   Design the Circuit   The resistors are 1%.  To work prope ...
I am posting my initial impressions of the Multicomp Pro Handheld LCR Meter.  My objectives are to get familiar with the capabilities and use of the meter, do some comparisons to other instruments in my possession, and summarize my impressions in a way that might prove useful for other electronics enthusiasts. Background   I am constantly trying to upgrade my bench and this is the first really capable LCR meter I have owned.  It was definitely a want as opposed to a need but a ...
This is a quick overview and initial impressions of the Tenma 72-9380A multimeter.  A comparison is made to other multimeters I currently own and use. Background   I currently own 4 multimeters that I frequently use, one of which has been on the blink.  So when I won a recent Project14 contest it was an opportunity to replace it at the right out of pocket cost (no out of pocket cost).  I am an electronics enthusiast and my criteria for instruments differs from those who w ...
The milliohm meter has been one of the most popular projects I've posted on element14 judged by views, comments, and stated interest.  Thanks to a modification by shabaz (documented way down in the comments here) and much help over time it appears to have reached or is very close to the design objectives: Low cost Dual range covering from 1 milliohm to 40 ohms Choice of power source - USB or batteries Kelvin (4-wire) probes Low current (1 to 10 mA) through the Device Under Test (DUT) ...
Every summer I do a "camp" with my grandchildren where the theme is electronics and robots.  This year was a bit more complicated due to the pandemic with me moving in the middle of it and not having my electronics lab for several months.  I had originally planned to design an educational robot but events put an end to that.  So I ended up buying the Lego WeDo 2.0 educational kit which is widely used in schools.  My two oldest grandchildren came over and stayed for 3 days and ...