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RE: TLE94112 Interactive Testing Platform

dubbie — Fri, 07 Aug 2020 11:20:07 GMT

Enrico,

A very interesting project. I have investigated systems for obtaining the characteristics of DC motors previously, but without much success as it all seems very dependent: dependent on the on the load, on the power supply, on the temperature, the age of the motor, with the controller seemingly a distant partner. Have all your tests been performed with no-load? I always found it very difficult to create/obtain any form of quantifiable load when doing this. Most seem to be friction based but they are difficult to convert the load/friction into a measurable load value.

I tried learning the harmonic once and after about six months I proudly visited my mother to show her my progress. She remarked brightly that she used to play one in her youth and promptly proceeded to play far batter than me, despite not having touched one for forty years or more. I put my away and never played again. Pretty much the same story with a guitar as well. And the piano. And the drums. I can sing but musical instruments just elude me. My parents also had a dog - which was fun, but now I prefer other people's dogs, so much easier.

Dubbie

RE: TLE94112 Interactive Testing Platform

wanfp97 — Thu, 06 Aug 2020 17:20:58 GMT

Hi Enrico,

I am recently dealing with the TLE94112 shield and I found this helpful post. I'm completely new on this, do you have any suggestions for me to learn how to control it using a XMC from Infineon?

Fook Peng

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

cpprioli — Fri, 27 Mar 2020 14:45:31 GMT

I realize that this is a late date for this, as most of the comments are older.

I built one of these tachs a few months ago, and was recently looking at the availability of some of the conponents used in its construction

If anyone is interested, I currently have spares on the items listed below. If anyone is interested in building this unit and has difficulty in locating certain items, All of these items are available in limited numbers, at my cost for the item(s) plus appropriate shipping. Post back here to start a dialog and we can work it out so that you can get the needed items.

Available Special Components for this Project:

SD5620-001 OptoSchmitt Detector (4)
VSLY5850 850nm Infrared Emitter LED (4)
MCCOG21605B6W-BNMLWI LCD Unit (1)
20021121-00010C4LF 10-pin SMD Header (2)
OS102011MA1QN1 90° Slide Switch SPDT (2)
B3F-1070 Tactile Pushbutton Switch SPST NO Momentary (4)
B32-2010 Key Cap for Pushbutton Switch (4)
R-78E5.0-0.5 DC-DC Converter 500mA 5V (2)
MCP1702-3302E/TO 3.3V LQC/LDO Voltage Regulator (4)
BC547C Transistor, NPN SI GP Amp/Switch 45V 100mA (34)
X32K768L104 Crystal 32.768kHz (4)
PCB_Cyclops_Tach_v1.0 Printed Circuit Board (4)
MSP430G2553IN20 MCU, written with your choice of original code or updated code (7)

In addition, all hardware and passive parts, including the enclosure, are also available, though these are all readily available from many suppliers. I also have available a supply of clear plastic sheeting for use as the case lens and black card stock to use for LCD edge blackout. it is even possible for me to put together complete build kits for this tach.

I am NOT looking to make any money on these items, but rather to make them more available for those who may not be able to source them readily. The quantities shown in parentheses above are those that are on hand as of this posting.

I hope that this can help somebody, especially someone who is serious about building this useful tachometer. Good luck, and happy building!

RE: Project14's DIY Test Equipment: DIY Constant Current Load

michaelkellett — Mon, 06 Jan 2020 10:20:21 GMT

One point to be noted is that at 1 Amp of current, the drop on Rsense would be 1 Volt and with the Vgs required to be more than 10V for the IRFZ44N and 4.5V for the MTP3055, the gate voltage should be as high as possible. This would also go on to effect the switching times with the Vgs rise time not being able to meet it’s intended mark.

I looked at the data sheet for the IRFZ44N from IR, especially this graph on page 3:

[View:/resized-image/__size/426x375/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-a375dca5-7cdd-4061-94d1-04f498753396/contentimage_5F00_205638.png:426:375]

You can see that typically you will need a lot less than 5V Vgs to get 10A of drain current - so you should be able to run you op amp from a 9V supply.

Another point that may be helpful, whenever I put a buffer in the feedback loop of an op amp I add some defensive components:

[View:/resized-image/__size/341x325/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-a375dca5-7cdd-4061-94d1-04f498753396/contentimage_5F00_205639.jpg:341:325]

R1 helps to protect the op amp from the capacitive load presented by the MOSFET gate.

It also slows things down, make it too big and the MOSFET will take ages to turn on.

C1/R3 reduces the gain in the loop at high frequencies, many op amp/MOSFET combinations are unstable.

The best way to tune (in Spice or hardware) -

start with the values shown, drive with pulses or square wave.

Adjust R1 to get fast enough response (check op amp specs for recommended minimum series R driving a capacitive load).

Adjust C1.R3 to get best (smallest) overshoot (increase R1 or C3), and best response time (decrease C1 or R3)

As long as your op amp is unity gain stable you can tune this design to be stable with pretty much any MOSFET and op amp - high Q inductive loads can be a problem.

All the above applies if you are using the MOSFET as a current sink or a voltage follower where R2 is the actual load.

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

Andrew J — Sun, 05 Jan 2020 22:17:27 GMT

Not sure why this has popped up in blog posts but I haven't forgotten about this! I've struggled to get it calibrated - wouldn't read any LEDs operating on mains consistently and even against the Bombe itself I'm struggling to get a reading. I have put some debug code in to see when it is in a 'working-but-discarding' phase and it is showing widely varying values there so not settling. Having said that, I've not been able to spend any time with it measuring the Bombe's motor speed because we've been busy replacing worn parts and fixing timing problems with the commutators and capacitor discharges (which we still call condensers on the machine [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-168040e1-7b2b-4d3e-a37f-100ff564be34/0383.contentimage_5F00_1.png:16:16]) affecting the mechanical relays. I've not wanted to disrupt that with my own testing but I am hoping that now we've sorted that I may get some time to look more into the readings. It was working ok with the V1 code, albeit not accurately because the motor speed is so low - at full speed it is 600rpm at spec but likely to be around that rather than exact. I did once get a steady reading at 580RPM and that feels about right, but only the once unfortunately.

Anyway, the point is that I haven't forgotten and will let you know!!

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

shabaz — Thu, 08 Aug 2019 17:20:07 GMT

Hi! This project has been updated, with an 'August 2019 Update' section in the blog post.

It covers revision 2 code, which is a lot more accurate+granular (a hundred times more granular, to 2 decimal places).

However revision 2 code will need calibration to get the accuracy (calibration is easy, it is described in the blog post update).

Incidentally it can also detect the frequency of operation of infra-red remote controls.. pointing it at the sensor and pressing a button will show the frequency (e.g. 37kHz or whatever).

RE: DIY Test Equipment: The Di-o-Matic, a Simple Diode Tester [Arduino]

kristotlego — Sun, 05 May 2019 06:12:48 GMT

Where's the code? Please share it.

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

msbettyhunt — Tue, 23 Apr 2019 12:55:32 GMT

Excellent work! Thanks for sharing and explaining the every step of the project deeply.

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

three-phase — Sat, 09 Mar 2019 21:17:25 GMT

Great little project.

If there will be problems getting hold of the sensors, I wonder how much of a job it would be to modify this to work on a stroboscopic principle, using an LED and equating its flicker rate to an rpm reading on the display?

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

Andrew J — Thu, 07 Mar 2019 22:07:30 GMT

Well, here's a finished article! What a great project. I learnt a lot: as per usual, IC pins always draw blood when extracting from sockets [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-168040e1-7b2b-4d3e-a37f-100ff564be34/1050.contentimage_5F00_1.png:16:16]; a good soldering iron is worth its weight when you are new to it; measure a hundred times, drill once - measure 15 times, drill once and miss - I need to re-do the button hole and provide a grommet (and button cap) to cover the large hole. I could also do with some form of panel cover for the messy screen hole - which is actually better than it looks, but not great.

This will come in very useful at the museum, thanks Shabaz.

[View:/resized-image/__size/620x827/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-168040e1-7b2b-4d3e-a37f-100ff564be34/8233.contentimage_5F00_205551.jpg:620:827]

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

dubbie — Thu, 07 Mar 2019 09:39:51 GMT

Shabaz,

I really complete and useful project. I have sometimes found myself in the past wanting to measure the speed of various motors and wished I had something like this. I've never quite gotten around to making one (or buying one) but this is inspiring so maybe I'll do something, especially if I can combine it with something to do with a mobile robot. I'd have to use an Arduino as well.

Dubbie

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

Andrew J — Wed, 06 Mar 2019 16:11:53 GMT

Hi Shabaz,

so, I've finally gotten around to making this - I had a couple of projects to finish off first. I've reached the point of soldering on the LCD, diode and photodetector and wondered if you had any tips for these? I'm not that experienced at soldering - this is my second serious soldering project - but I do have a good iron. The LCD pins are very fine and the pads very close together. I also wondered if it was better to solder the diode/PS on the board, or cut their holes in the case and work it from there? For example, do they need to be fully in the case, just sticking out or some other position?? Perhaps I'm over thinking it but, as you know, that PS is difficult to get hold of and I only have the one; I also don't want to damage the LCD.

Thanks,

Andrew

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

Andrew J — Mon, 10 Dec 2018 14:24:59 GMT

Is there an alternative to the MSP430G2553IN20? Farnell's (UK) have this tagged as 'whilst stocks available' and the Dev board, MSP-EXP430G2, is no longer stocked and MSP-EXP430G2ET isn't part of inventory. Other sellers have them of course.

This project would be ideal: we maintain a very old electro-mechanical machine and an issue was caused by a motor/clutch not running to spec. It was spinning slightly too fast, although in fairness it was ultimately due to a slightly incorrectly sized drive belt. Adding this to our toolkit would be very useful.

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

lpridgen — Wed, 24 Oct 2018 23:27:51 GMT

Hi Shabaz,

Finally got the correct part and finished the project.

Cheers

Laz

RE: Cyclops-1000: An Electronic Eye for Rotational Speed Measurement

lpridgen — Wed, 24 Oct 2018 23:25:56 GMT

[View:/resized-image/__size/675x900/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-168040e1-7b2b-4d3e-a37f-100ff564be34/contentimage_5F00_205550.jpg:675:900]