MicroAmp-Meter based on Dave,s design (Designing A Better Multimeter) - Page 1
Forum section: electronics / general

author: farzansaleem
author_rank: Contributor
timestamp: April 20, 2023, 05:22:54 pm
content: Hello everyone!My name is Farzan and I'm a developer at Bosch Kft in Hungary.We have developed MicroAmp-Meter which is a current measurement tool featuring auto-ranging, Wi-Fi current profiling, SD card logging options, and more. It is a portable current meter that can record and profile the current consumption of devices in real time.The shunt-switching topology is based on David Jones's designEEVblog #929 - Designing A Better Multimeter.We're raising funding through Kickstarter at an affordable price, please take a look at our Kickstarter project below!https://www.kickstarter.com/projects/microampmeter/microamp-meter?ref=bannerhttps://www.danalogx.com/

author: thm_w
author_rank: Super Contributor
timestamp: April 20, 2023, 09:51:33 pm
content: Looks good.So USB power and DUT power are completely separate?What are the voltage in/out connectors, JST?What is the reason voltage in is limited to 9V?

author: farzansaleem
author_rank: Contributor
timestamp: April 21, 2023, 07:46:40 am
content: Hello,Thank you for the nice feedback.USB is for charging only so yes, USB power and DUT power are completely separate. The current consumption is measured through Voltage IN/OUT connectors.Voltage IN and OUT connectors are 2.0mm JST connectors for attaching Power Supply and Load separately. It is designed in such a so way that people can attach their product battery directly to the MicroAmp-Meter for field testing (almost all batteries have 2.0mm JST connectors).The product is designed to measure the current consumption of embedded devices especially targeting the IoT sector which normally operates at 5V or less. So in the design phase, we were thinking to make it up to 5V. But then we realize that some people also use 2s batteries in their IoT products, which is why we have increased the voltage limit range up to 9V. Another reason is that some sensors operate at more than 5v e.g. The minimum operating voltage for the popular ultrasonic chip PGA460 is 6V.

author: PlainName
author_rank: Super Contributor
timestamp: April 21, 2023, 08:53:19 pm
content: How come Kickstarter says "DANALOGX Inc London, UK" but you're in Budapest?What ballpark cost are we looking at for this?

author: farzansaleem
author_rank: Contributor
timestamp: April 21, 2023, 09:06:03 pm
content: This is because Hungary is not a listed country for Kickstarter. So we registered a company and we will launch it from the UK.The launch price on Kickstarter is 80 pounds. Please subscribe to our Kickstarter campaignThank You.

author: mariush
author_rank: Super Contributor
timestamp: April 21, 2023, 10:20:15 pm
content: I would want such product to support at least up to 12v.We see with 12v0 that computers will probably transition to 12v stand-by.There's lots of power adapters that power routers and cable modems and various things that work with 9-12vUSB power delivery / quickcharge has 5v / 9v / 12v and 20v (but not all chargers go higher than 12v or 15v)If you're aiming for very low currents, why use connectors that require usage of such small connectors, don't you want reasonably thick wires for low voltage drop and all that?Why not use something super common like mini-fit series (atx , cpu, pci-e connectors) which accept up to awg16 wires and they're mass produced, easy to find, easy to crimp pins to wires etc etc easy to make adapters ex barrel jack to 2-4 pin mini fit (just get a pci-e extension from some store, cut the wires, solder the wires to barrel jack to make your own adapter.May not have the vertical height for a 4 pin cpu / pci-e connector but maybe you could make your product more tall but less wide or whatever.I'd want at least 2 decimals for voltage measurementI'd want a monospace font used for those numbers under the digits, and maybe have the digits aligned to the right. Don't want the whole row of text or just the numbers to wiggle left and right depending on how wide the characters are (ex 0.112mA vs 0.860 mA - that font looks like it would have different width for the digits.if it has a built in websocket application , logged data could be downloaded through that ... so may consider making internal storage an option or releasing a model without SD slot for those who want higher resistance to water for example. A 2 gbit (256 MB) SPI flash chip with SLC memory and 100k erase cycles is not expensive at under 3 dollars -example hereand could even be soldered to a thin pcb to make it removable / replaceable if it wears out.80 pounds is a bit much ... maybe consider making a light version with a monochome lcd display (potentially transflective so no backlight needed) with segments instead of full color display? there's an initial cost of a few hundred dollars to design the lcd screen but afterwards each display is cheap.or use something ready made like sharp 128x128 pixel 1.28" for 6$ in quantity (but your color lcd may be cheaper than this) :https://www.digikey.com/en/products/detail/sharp-microelectronics/LS013B7DH03/5300387

author: PlainName
author_rank: Super Contributor
timestamp: April 22, 2023, 10:28:05 am
content: Quote from: farzansaleem on April 21, 2023, 09:06:03 pmThanks for that excellent explanation

author: farzansaleem
author_rank: Contributor
timestamp: April 22, 2023, 07:55:05 pm
content: Quote from: mariush on April 21, 2023, 10:20:15 pmThank you for the long feedback.The product is not designed to measure the current of routers/modems as they consume way more than 1Amp current. But we are considering to increase the range up to 12v.Regarding connectors, MicroAmp-Meter will be shipped with 20AWG wires and that is a reasonable gauge for current up to 1Amp. The voltage drop would be less than 20mV, which is neglectable. There is no need for bulky ATX connectors for this product.As you have suggested we will add 2 decimal places for voltage.We have spent a lot of time designing UI. We have come up with our best possible user-friendly design. Your suggestion will cause the wiggling of decimal point from left to right which will create a lot of confusion, especially with the fast-changing current.Regarding SPI flash we are already thinking about this in the next model.80 pounds is a very reasonable price keeping in mind the cost of expensive analog frontend, LCD, battery, casing, assembly cost, duty customs, etc. We have also spent a lot of money on R&D and a lot of time on the development of this product.We also plan to launch the MicroAmp-Meter Lite version in the future for less than 50 pounds. That will be a bare PCB variant without a battery and a small LCD.

author: PlainName
author_rank: Super Contributor
timestamp: April 23, 2023, 12:05:19 am
content: QuoteI am looking at the example video (or gif) and the decimal point is moving, presumably because the digits are centred. For something like this the digits should be static. Suppose the current changes between 10.1 and 9.9 - the digits are shuffling back and forth and it's very distracting.Since you have a single digit after the point (soon to be two, maybe) I think right justifying would ensure the decimal point is fixed in place and everyone would be happy. After all, the bigger the number the further left it will stretch, which is meaningful without reading when the number is.However, note that the above assumes you use the full width of a 0 when placing digits, even when the actual digit is not the full width. If you're treating a 1 as only the width of the displayed segments then it will be truly horrible because it will jump around (like in your video).Re pricing: I would probably buy one for £80 - the value is not so much in the component cost as the development work, and with a relatively small market (until someone in China copies it) the overheads are significant. It would easily cost me that to try and make one myself (although then I could suit myself about how the digits are displayed).

author: mariush
author_rank: Super Contributor
timestamp: April 23, 2023, 05:44:04 am
content: Quote from: PlainName on April 23, 2023, 12:05:19 amYeah that's what I was referring to... keep the digits fixed like on multimeters, maybe even give them a small angle in the case of big digits.For the Iavg and mAh, use fixed width digits, and I'd suggest fixing the Iavg and mAh to left and/or right corners, the measurement unit fixed to the other side, and the digits right justified and fixed widthSee picture below...Iavg moves around, the string expands and shrinks according to width of digits, 1 uses less space than 0 and so on....there's lots of nice bitmap / monospaced fonts available for free on sites like dafont.comfor examplehttps://www.dafont.com/dogica.fontorhttps://www.dafont.com/freecam.fontorhttps://www.dafont.com/pixel-operator.fontorhttps://www.dafont.com/rainyhearts.fontorhttps://www.dafont.com/lggothic.font... lots of them.Some more comments about screen... I would be pissed that you're wasting so much screen real estate with that MicroAmp-Meter text ... have a logo at boot or something, then make that go away and have the big digits up, then a second row with the average and mAh.You could put the text on the title bar where the Danalogx is if you insist on that.Seems like there's enough for 8 digits and dots between them. Would probably be better to keep it symmetrical and maybe that could be better because it makes it possible to do option to show only current or only voltage, and you'd have more decimals for current them (ex keep showing value in uA when you're reading a 1..10 mA range)If that red bar at the bottom only says logging disabled, it would also annoy me. That could time out after 10-20 seconds and fade out or something and a red icon could be put on the title at the top, maybe even blinking, indicating logging is disabled.As the bottom bar fades or slides down, you could switch to bigger digits for the second row, or shift it down a bit to be vertically centered... or whatever.For the big digits, if you have a rgb screen, you could probably add an option like making the digits green when it's uA and yellow or cyan or some other color blind friendly color on mA ... voltage could be red. This way user knows the unit without having to move eyes to the bottom row under the digit. Speaking off ... more wasted space giving uA / mA and V a whole lot of vertical space.With the big space used by the micrometer text and the red bar fading out, maybe you could implement some horizontal graphing at the bottom ...like let's say 32-64 pixel tall strip with horizontal scroll showing the variations in current, this way user would see current bursts or whatever .. could be one horizontal pixel for every 10-20 measurements averaged or something like that.

author: PlainName
author_rank: Super Contributor
timestamp: April 23, 2023, 09:47:08 am
content: QuoteI like that idea

author: farzansaleem
author_rank: Contributor
timestamp: April 24, 2023, 11:43:54 am
content: Quote from: PlainName on April 23, 2023, 12:05:19 amThank you guys for the suggestions. I would work on these features, especially with the center alignment of the text. I will try to adopt the fixed decimal point feature like Multimeters. At this stage, we will not be able to add an LCD plotting feature.Yes, it is possible to make similar devices by ourselves or to be copied by Chinese because I have already mentioned that shunt switching topology is open source and has been adopted by the design provided by Dave. It is the complex software that is the IP of this product. This device is running more than 3000 lines of code and WEBGL implementation for plotting more than 200K points on the web browser. Being able to create something by yourself does not mean you shouldn't give a try to other productsWe are a bunch of hobbyist guys who did not have a fancy marketing budget and just rely on these types of forums. I am attaching the Kickstarter promotional video to the forum (Sorry for the low-quality because of the file size limit). Please have a look at the WebSocket application feature.That post has been viewed by a lot of people but very few have subscribed to our campaign. I don't know if this is because of the price or something else. Because of that, I am creating a poll so if you are reading this post please spare some time to vote on the poll.Thank You.

author: PlainName
author_rank: Super Contributor
timestamp: April 24, 2023, 11:13:58 pm
content: Don't read anything into the number of views. It's like assuming the number of Google results for something is meaningful.Personally, I haven't subscribed to your campaign because I am not sure I will buy one. I want to see where it goes and how this progresses, first. But mostly because I don't need or want even more spam. If/when I am interested in seeing what's been going on I am fully capable of just going along to take a look.

author: Pinkus
author_rank: Frequent Contributor
timestamp: April 25, 2023, 08:54:05 am
content: Looks good!And around 90 euros seems OK for such a useful tool.However, as I read your description, a few thoughts came to me about what I (and I'm sure others) would probably be missing quickly and what limitations therefore might stop me from buying. I'll write them down below, maybe they'll be helpful:1) I often have measurements where I am indeed interested in the low µA-Range standby current, but the unit needs way more than 1A when switched on. An extension with a fourth measuring range (which doesn't have to be super accurate) 1-10A would be ideal (at least 5A), especially since the log function would also allow to log current consumption over a longer period of time, this would be very useful.2) Also important for me: I do not want to connect the unit to a PC all the time if I do a quick measurement. Then I just want to quickly analyze some basic data. Sometimes I just quick information like:· actual current· maximum· minimum· average over the whole measurement cycle (you do only average over 1 second)· switch to a graphical display (curve) of the current cycle (best with some x-axis presets like whole cycle/last minute/last 10s/last s/last 100ms/last 10ms/last 1ms).

author: farzansaleem
author_rank: Contributor
timestamp: April 29, 2023, 10:33:40 am
content: Quote from: Pinkus on April 25, 2023, 08:54:05 amI did some experiments with decimal fixing and also adding max/min values on display. I will improve it later.At this point, it is not possible to increase the current range but I will definitely increase the range in our upcoming product.We are about to launch on Kickstarter. Please support this project.https://www.kickstarter.com/projects/microampmeter/microamp-meter

author: farzansaleem
author_rank: Contributor
timestamp: May 01, 2023, 08:38:19 am
content: Quote from: farzansaleem on April 20, 2023, 05:22:54 pmMicroAmp-Meter is live on Kickstarter.https://www.kickstarter.com/projects/microampmeter/microamp-meter?ref=creator-nav

author: PlainName
author_rank: Super Contributor
timestamp: May 01, 2023, 09:52:14 am
content: Looking forward to receiving mine in September

author: Mr.B
author_rank: Unknown
timestamp: May 11, 2023, 04:41:27 am
content: What is the largest capacity SD card the device will support?

author: David Hess
author_rank: Super Contributor
timestamp: May 11, 2023, 02:24:15 pm
content: I lost interest after I found no noise or drift specifications. Is the included filtering because of noisy loads or because of inherent noise? There is no way to evaluate the useful resolution.

author: farzansaleem
author_rank: Contributor
timestamp: May 15, 2023, 07:32:43 am
content: Quote from: Mr.B on May 11, 2023, 04:41:27 amThe maximum size for SDHC card is 32GB. SdFat also support larger SDXC cards up to 512GB but it is recommended to use 64GB or less.

author: farzansaleem
author_rank: Contributor
timestamp: May 15, 2023, 07:34:40 am
content: Quote from: David Hess on May 11, 2023, 02:24:15 pmNo issue you can change your mind anytime. But thank you for the tip. That information should be present over there. I would try to add it ASAP.

author: ebastler
author_rank: Super Contributor
timestamp: May 16, 2023, 08:18:20 am
content: Since fonts were discussed earlier: May I suggest that you move away from the typewriter-style (monospaced serif) font for the smaller text? For some reason, that style has become a hallmark of cheap Chinese products, and you probably don't want that association. Also, especially with smaller text, the serifs do not help readability. A sans-serif, variable width font would be preferred in my view.