Timeline for 24V H-Bridge DC motor, why voltage drop to 3v if motor connected
Current License: CC BY-SA 3.0
17 events
| when toggle format | what | by | license | comment | |
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| S Jul 5, 2014 at 14:45 | history | suggested | LorenzoDonati4Ukraine-OnStrike | CC BY-SA 3.0 |
Fixed typos and grammar. Retagged; L298N is just an L298 (N indicates the package), so no need to have a specialized tag for it. Used more specific tag.
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| Jul 5, 2014 at 14:14 | review | Suggested edits | |||
| S Jul 5, 2014 at 14:45 | |||||
| Aug 9, 2013 at 5:27 | vote | accept | Athelstone | ||
| Aug 4, 2013 at 7:00 | answer | added | Athelstone | timeline score: 1 | |
| Aug 2, 2013 at 18:19 | comment | added | Athelstone | @pjc50 : Connected and driven (logic 10 is being fed). The PSU is OK (motor rolling if connected directly to PSU). Yes, their ground are connected together. | |
| Aug 2, 2013 at 18:13 | history | edited | Athelstone | CC BY-SA 3.0 |
Correcting typo, 2N3904 instead of 2N3906
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| Aug 2, 2013 at 18:06 | comment | added | Athelstone | @Tut: Sorry, it's a typo. You're right, it's 2N3904 that I actually use. | |
| Aug 2, 2013 at 12:27 | comment | added | pjc50 | I'm also suspicious of putting the outputs in parallel like that.. | |
| Aug 2, 2013 at 12:19 | comment | added | pjc50 | (the logic ground and 24V power ground are definitely connected together, yes?) | |
| Aug 2, 2013 at 12:19 | comment | added | pjc50 | If you are measuring 70ma @ 3.3V on the input to this circuit, then it's definitely the fault of the power supply. When you say "it drops to 3.3V when the motor is connected", do you mean connected and driven or does it fail even when the motor is not being driven? | |
| Aug 2, 2013 at 12:12 | comment | added | Athelstone | @JIm Dearden : Wiring should be OK since if motor is unconnected the circuit works as expected (motor terminal J1 provides 24V on logic 10 and reversed polarity on logic 01). The motor has no load attached, so it's torque resistance should be at minimum. For logic, I'm simply connect it to ground for logic 0 and 5V for logic 1. 5V power rail come from different source (7805 regulated from 9V power supply, too much voltage burned for using 7805 from 24V supply) with both shared ground. | |
| Aug 2, 2013 at 11:48 | comment | added | Athelstone | @pjc50 : 70 mA @ 3.3V. It does current limiting at 10A. I've tried connect the motor directly to PSU, and the motor roll OK, so neither PSU nor the motor itself has problem. | |
| Aug 2, 2013 at 11:15 | history | edited | Phil Frost | CC BY-SA 3.0 |
add links, inline schematic
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| Aug 2, 2013 at 9:22 | comment | added | Andy aka | What logic supply are you using? | |
| Aug 2, 2013 at 9:10 | comment | added | JIm Dearden | The L298N is a very reliable chip, the reference circuit looks ok so perhaps the fault is with your wiring. BTW the current a motor draws is determined by the load (torque). You can't simply use ohms law by measuring the resistance and dividing that into the voltage rating. The back emf generated when the motor turns will reduce the effective voltage across the resistance so I = (24 - Vback)/7.5 - a much lower value than you calculated. The 3.2A is the stall current . | |
| Aug 2, 2013 at 8:58 | comment | added | pjc50 | Are you sure the power supply isn't current-limiting? When the voltage drops to 3V, how much current is drawn from the supply? | |
| Aug 2, 2013 at 8:37 | history | asked | Athelstone | CC BY-SA 3.0 |