Exact same ammeter different supply voltages - Page 1
Forum section: electronics / beginners

author: dclevy1
author_rank: Contributor
timestamp: March 22, 2018, 10:13:06 am
content: I have two of the exact same model ammeters I bought them at different time periods. One of them has a supply voltage of 5 volts the other has a supply voltage of 8 through 18 volts( the one with the extra three components on it). So my question is if I remove these three extra components could I Supply this meter with 5 volts like the other one and be okay? It seems like the three extra components or a voltage regulator, a possible buck converter and a capacitor. Both of these are yb5145b-v1.1Sent from my iPhone using Tapatalk

author: Zero999
author_rank: Super Contributor
timestamp: March 22, 2018, 11:20:30 am
content: If one has extra components then the two ammeters can't be exactly the same model.It's quite likely that the one designed for 8V to 18V operation, is the same as the 5V model, just with an extra voltage regulator, which can be removed or bypassed for 5V operation, but check the data sheet and schematic (reverse engineer it if necessary) first.

author: rstofer
author_rank: Super Contributor
timestamp: March 22, 2018, 02:06:11 pm
content: In the first photo, the voltage regulator that drops the voltage down to 5V is not populated so that would be the 5V meter. In the other photos it is and those could be fed by 8V+.Check the part number on the regulator. If it is something as simple as a 7805, you can simply remove it and the other two components (I didn't chase these) and feed the meter with 5V. Wire it just like the other meter.

author: Zero999
author_rank: Super Contributor
timestamp: March 22, 2018, 02:29:55 pm
content: Oh there are some pictures? I can't see them, because I'm behind a strict firewall at the moment. Please attach the files, rather than using an external file hosting service, failing that, I'll look later.

author: dclevy1
author_rank: Contributor
timestamp: March 22, 2018, 02:34:28 pm
content: Quote from: Hero999 on March 22, 2018, 02:29:55 pmThey are attachmentsSent from my iPhone using Tapatalk

author: dclevy1
author_rank: Contributor
timestamp: March 22, 2018, 02:37:11 pm
content: Quote from: rstofer on March 22, 2018, 02:06:11 pmIt is in fact a l7805cv. So simply removing the three components can allow me to run it at 5 volts right?Sent from my iPhone using Tapatalk

author: dclevy1
author_rank: Contributor
timestamp: March 22, 2018, 02:38:31 pm
content: Quote from: Hero999 on March 22, 2018, 11:20:30 amThey are indeed the same model it is printed on the circuit board just with different voltage requirements due to extra components put in place holdersSent from my iPhone using Tapatalk

author: Zero999
author_rank: Super Contributor
timestamp: March 22, 2018, 02:49:04 pm
content: Quote from: dclevy1 on March 22, 2018, 02:34:28 pmNo they're not. You've uploaded them to another site and adding them by using image tags. To attach images, click Attachments and other options at the bottom of the text box, when making or editing a post.Quote from: dclevy1 on March 22, 2018, 02:38:31 pmThen the PCBs are the same, which doesn't mean they're the same models. Quite often manufactures use the same board design, for the same parts, even if the schematics differ.

author: rstofer
author_rank: Super Contributor
timestamp: March 22, 2018, 03:39:25 pm
content: Quote from: dclevy1 on March 22, 2018, 02:37:11 pmThat would be my GUESS! Check that the PCBs are otherwise identical in the area of the regulator and give it a try. Be certain you duplicate the wiring exactly.

author: RobertPS
author_rank: Contributor
timestamp: March 22, 2018, 03:52:46 pm
content: It's the same board wth a different configuration on it. You need to both identify and understand the differences.Check the presence and values of all components including jumpers.For example C11 is not present on the 8V+ board but it is on the 5V board. On the 8V+ board you have C14 present but not on the 5V board.

author: dclevy1
author_rank: Contributor
timestamp: March 22, 2018, 05:13:35 pm
content: Quote from: RobertPS on March 22, 2018, 03:52:46 pmDamn it right I did realize about the c14 but I did not notice at all the c11. Nor do I have surface mount capacitors like that. Nor do I have the skill and patience to sit there and solder surface mount capacitors that small. Damn I wonder if there is a extremely small 5 to 12 volt step up converter?But I don't think I explain why I need this to be 5 volts similar to the other one but I already created an application to accommodate one of the ammeters and I was adding another to modify my current application. Upon ordering I realize that they didn't have any more 5volt ammeters of the same model only +8volts soooooooo yeahSent from my iPhone using Tapatalk

author: glarsson
author_rank: Frequent Contributor
timestamp: March 22, 2018, 06:33:28 pm
content: Many designs, Arduino boards as an example, that can take both a varying voltage (like 8-12V) and 5V simply connect the 5V input directly to the output of the regulator. This way the 5V input is also an output. You can do this IF the voltage regulator can live with unconnected input and 5V on the output. Finding a spot to solder the 5V input is a lot easier than replacing surface mount components.

author: dclevy1
author_rank: Contributor
timestamp: March 22, 2018, 08:00:05 pm
content: Quote from: glarsson on March 22, 2018, 06:33:28 pmI will look into this and test this out as well but I will probably just buy and use a step-up converterSent from my iPhone using Tapatalk

author: dclevy1
author_rank: Contributor
timestamp: March 22, 2018, 08:03:13 pm
content: Thank you all for your help I really appreciate itSent from my iPhone using Tapatalk