View Full Version : tohmm TOH Multimeter
https://pbs.twimg.com/media/BkusonRCAAA4BcG.png
Multimeter
Icon by solbrit
New TOH idea by bill_klpd, Multimeter TOH.
Seems that i started to think about this further.
First, sketching the UI:
https://lh6.googleusercontent.com/-0e6qtSPRR3I/U0TxW5yQNFI/AAAAAAAAG-o/O0k-U4OpPc4/w590-h1048-no/20140409100124.jpg
Block diagram of the electronics part: (First draft)
https://lh5.googleusercontent.com/-v4RoluPFzHc/U0WUKuLfnAI/AAAAAAAAG_I/UB7Fg07qRMg/w1044-h486-no/tohmm100.png
First 3D sketch:
https://lh4.googleusercontent.com/-LdcYB9H30KU/U0a11xUTBnI/AAAAAAAAG_Y/p1vgsD9iae8/w1162-h1359-no/tohmm-mockup-1.png
HW Specs:
Voltage measurement ranges 200mV, 2V, 20V, 200V DC (AC TBD)
Current measurement 200mA, 2A (TBD)
Resistance measurement 200, 2k, 200k, 20MEGohms (TBD)
Possibility to measure low-side current and high-side voltage at the same time --> Power (W) measurement.
Isolated from phone (floating) should be safe to keep USB charger connected while taking measurements.
Fused current measurement
SW Specs:
Continuous measurements with adjustable rate
Min/avg/max display
Single shot measurement when in hold mode
Beep when new min max value, or beep when short in Resistance mode.
Logging of readings with timestamps
Trigger events with alerts also possible TBD
"Plotter" view on separate page of latest results TBD
or simpler graph view in main page TBD
future is coming!
also please add short circuit mode checking with beep signal.
future is coming!
also please add short circuit mode checking with beep signal.
Hmmh, why not an oscilloscope, or at least a possibility to plot voltage changes over time... :D
Usually multimeter functionality is implemented by sampling the voltage in analog hold, and then measuring the time differential when bleeding it off through a known resistance. (this allows for really accurate measurement with no A/D converter needed, and is easy/cheap to implement with a dedicated chip).
However with a real fast-sampling A/D conversion it woud be possible to get the waveform plot too.
why not? i'm just asking what i want :)
why not? i'm just asking what i want :)
Sorry, I meant to add a post, not reply to yours!
Continuity beep is a good feature, yes.
However, what I'd like to have is the scope mode :)
Hmmh, why not an oscilloscope, or at least a possibility to plot voltage changes over time... :D
See specs ^^
Note; This is not a oscilloscope. That toh will be done later with its own micro to buffer/preprocess samples.
Usually multimeter functionality is implemented by sampling the voltage in analog hold, and then measuring the time differential when bleeding it off through a known resistance. (this allows for really accurate measurement with no A/D converter needed, and is easy/cheap to implement with a dedicated chip). For me that is also an A/D converter :rolleyes:
However with a real fast-sampling A/D conversion it woud be possible to get the waveform plot too.[/QUOTE]
Maximum samplerate with A/D converter selected (atm) is 860 sps.
400kHz I2C limits samplerate to about 7ksps, (at 16bits) but when taking IOCTL etc into account, maybe something like 10 sps in realtime could be doable without buffering...
(if taking samples in background for a short period of time, 860sps is doable)
I would really like to see a logic analyzer :)
I would really like to see a logic analyzer :)
Logic analyzer will be in tohscope
bill_klpd
2014-04-09, 08:58
Great work kimmoli! Keep up :D
Logic analyzer will be in tohscope
Then,
'should the f... up and take my money' :)
Please add me to be #1 :)
OMG! A multimeter, an oscilloscope... Will you please stop any time soon? You are making it harder and harder every day to keep resisting buying a Jolla! :)
nokiabot
2014-04-09, 13:15
omg ! i think you have gone mad or possibly a toh fever :D
Wow! Great work! Would like to have a Jolla right now!
No rush for this...
it will take some time before HW realized...
I would add the jolla to my multimeter collection then :p
This is too good to be true !!
Count me in :)
This is something which I have been wondering since I heard about jolla TOH. Count me in too!
I thought you were just working on an app but it's a new Kimmoli brand TOH. And a very interesting and ambitious one at that... I'm definitely in!
This is great idea for TOH, however the image of scared me. Where doesn fused go? We don't want any ppl to burn there devies.
Where doesn fused go?
Thanks for reminder... Added fused current measurement to specifications.
shadowjk
2014-04-13, 07:49
Where do I preorder? :)
seiichiro0185
2014-04-13, 08:05
Where do I preorder? :)
+1
I really like this idea :)
I'm in too. I kind of plan on collecting all Kimmoli's OH, I guess.
More detailed 3d. Trying to print this out prop tomorrow...
https://lh3.googleusercontent.com/-C54tA9nqoFE/U8P4mFPEGWI/AAAAAAAAHaE/Lsna_C4wPHY/w1742-h1083-no/tohmm-1-8.jpg
What's the current status of this?
What's the current status of this?
No progress... been too busy
its very interessting, think i want one, if the progree will be finished :)
Hi there! I was wondering how to develop a TOH oscilloscope: I have this max128B circuit already, and was thinking to use in place of ads1112-1, 6101fh, PCF8591 ADCs used by Kimmoli.
I'll start from this project and add my updates.
Actually the library is this one:
http://vesta.homelinux.free.fr/wiki/acquisition_senseurs_i2c_fonera_par_messages_xpl.h tml#Sh.C3.A9ma_du_circuit_Max128
Soon I will update the schematics.
Bye
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