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  • Why A DC to DC Converter Will Not Increase Range of the $3 Voltmeter Either

    From Bret Cahill@bretcahill@aol.com to sci.electronics.basics on Thu Apr 28 10:36:30 2022
    From Newsgroup: sci.electronics.basics

    Guessing that there was no clever end run around the 30v maximum I tried a DC to DC converter set to 15v then measured the voltage between the +38v and the +15v.

    Instead of 23 v it jumped around all over the place then settled on 3.x v.

    A cap between the terminals might not work either and may due to the fluctuating current short out the converter.

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  • From Bret Cahill@bretcahill@aol.com to sci.electronics.basics on Thu Apr 28 11:18:45 2022
    From Newsgroup: sci.electronics.basics

    Guessing that there was no clever end run around the 30v maximum I tried a DC to DC converter set to 15v then measured the voltage between the +38v and the +15v.

    Instead of 23 v it jumped around all over the place then settled on 3.x v.

    A cap between the terminals might not work either and may due to the fluctuating current short out the converter.

    Whoops! It works, at least for an 8 amp converter with a .270 amp load.

    The $3 volt meter reads a volt high, but once corrected the voltages add up only losing half a volt somewhere.

    Just add 14.3v to get the voltage and remaining range of the ebike.

    I will now try a 2 amp converter.
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  • From Jasen Betts@usenet@revmaps.no-ip.org to sci.electronics.basics on Thu Apr 28 19:31:57 2022
    From Newsgroup: sci.electronics.basics

    On 2022-04-28, Bret Cahill <bretcahill@aol.com> wrote:
    Guessing that there was no clever end run around the 30v maximum I tried a DC to DC converter set to 15v then measured the voltage between the +38v and the +15v.

    Instead of 23 v it jumped around all over the place then settled on 3.x v.

    A cap between the terminals might not work either and may due to the fluctuating current short out the converter.

    buy a better $3 voltmeter:

    https://www.aliexpress.com/item/4001035064897.html?spm=a2g0o.productlist.0.0.3ec85061Xtfaf4&algo_pvid=8b55bb0e-88bc-4587-b3e9-abf2fa2c8d6a&algo_exp_id=8b55bb0e-88bc-4587-b3e9-abf2fa2c8d6a-33&pdp_ext_f=%7B%22sku_id%22%3A%2210000013672700960%22%7D&pdp_npi=1%40dis%7CNZD%7C%7C1.84%7C%7C%7C%7C%7C%402101d4a716511737026983704e56e4%7C10000013672700960%7Csea

    One of those wires powers the display and wants no more than 30V
    the other one measures voltages upto 100V

    it may be possible to convert the one you already have to 3 wire operation.
    --
    Jasen.
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