Activity for mrbeanâ€
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Comment | Post #289688 |
@#36396 I hooked up three relay coils directly to the power supply set to 9V. The current read from the power supply was 16.6 mA (16.6 mA / 3 = 5.53 mA). The maximum current read from the DMM was 16.46 mA (16.46 mA / 3 = 5.49). I've switched the relay on and off several times using the output enab... (more) |
— | 8 months ago |
| Comment | Post #289688 |
@#36396 Thank you for the excellent answer! I have had issues with ground bounce due to the motor currents causing issues with other signals. I've had to be careful where I connect grounds of signals fed to an MCU. That very well could be what's happening. I will try investigating that further. ... (more) |
— | 8 months ago |
| Comment | Post #289710 |
Thank you for the excellent answer! I have had issues with ground bounce due to the high motor currents. So you may be right. I will try measuring the drive current as well and see what the coils are pulling for current. According to the TXS2-9V datasheet the coil resistance is 1157 Ohms and oper... (more) |
— | 8 months ago |
| Comment | Post #289688 |
@#36396 These relay coils are close to a motor. Do you think magnetic fields and di/dt in the motor windings could be inducing currents in the relay coils? Like a guitar pickup? (more) |
— | 8 months ago |
| Comment | Post #289688 |
The output section of the A2982 uses a darlington pair. The A2982 is similar to a ULN however the A2982 is designed to source current instead of sink current. That's good to know that they are notoriously brittle. That's what I've gathered as well after blowing two of the devices now. (more) |
— | 8 months ago |
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| Comment | Post #289688 |
I attached a schematic and added additional detail. Do the updates need to be approved? I am not seeing my update.
Edit: Looks like I needed to click the submit button twice because it was complaining about "alt text" for the images. I almost lost my work... whoops. (more) |
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| Edit | Post #289688 | Initial revision | — | 8 months ago |
| Question | — |
Burned Source Driver - Noise Spikes from Relay Coil I am trying to figure out what is causing an Allegro A2982 source driver to burn up. The source driver (A2982) is connected to the coil of a Panasonic TXS2-9V relay. The source driver and coil are connected by about 3 feet of wire. The source driver is on the high side and the coil is on the low... (more) |
— | 8 months ago |