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First of all, batteries have internal resistance. It will read lower voltage when current is consumed compared to no current being consumed, and your multimeter measurements confirm it. The ADC input impedance is not a problem, because it is optimized for source impedance that are 10k or less, and since you have a 10k resistor and 39k resistor the impedance ...


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Summary: Batteries are super difficult to measure. It sounds like you're already getting a decent measurement. It's probably best to stick with that and move on. In the title of your question you are asking about measuring the battery level (which I will interpret as "how much capacity is left"), but you are talking about measuring the battery ...


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All capacitative touch screen sensors have a reduction in sensitivity when the device is not connected to ground. When isolated from ground the device will have a capacitance to ground that is dependent upon the size of the device - for something the size of a cell-phone that capacitance is about 4pF and effectively appears in series with the touch ...


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There must be a stable ground reference to the touch layers and a stable reference capacitor (only film) to compare the change in C voltage (ac) wrt. gnd. to be a stable sensitive sensor. Without details, it is hard to point which ground link is missing when cables are disconnected or is there is another issue like excessive CM noise from RF(?)


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Full points for looking for a way to avoid running a generator simply to keep a gas furnace functional. Frame challenge: You won't gain enough efficiency to save any money, and the complexity will be an albatross around your neck. Wouldn't matter. You still have to power the furnace controls. And those require either 120VAC or 24VAC depending on the section ...


1

I have no idea (other than reading the other answers) about efficiency of different motor types. However, I don't think this plan is a good idea because you are adding significant complexity to a functioning system. Additional conversion (AC-DC) for the new motor. Backup power system for the motor, but still need backup power for the controls, igniter, etc. ...


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There are simple single phase BLDC motors for simple use. One I have saw was mounted on Husqvarna automower that propels the rotary knife cutter. They are produced by Emb Papst, I am not aware how exactly do they function, but it runs on Ni-MH battery and only one phase. See: BG3612


13

Brushed DC motors do not have the longevity of induction motors. They are also not particularly efficient. You may be able to find a BLDC motor with built-in control that could run from DC and be more efficient than a small induction motor. There is no motor type which can surpass an induction motor for longevity of service, although a BLDC can come close. ...


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Conventional DC motors with commutators are still somewhat viable for battery powered use, but they have steadily been losing market share because they are less efficient, less durable and have less longevity than AC motors. They once provided better performance for variable speed applications and had less complicated and more reliable electronic controllers....


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I ended up solving my problem by using an LM7812 linear regulator on the output of a 12V battery, then boosting it to 24V with a boost converter, then using an active rail splitter circuit with an LN1214CN op amp, and 2 x 12k resistors to produce +-12V rails with respect to a virtual ground - that being the output of the LN1214CN. See schematic below (excuse ...


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