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  • bardenbob commented on lonesoulsurfer's instructable Negative Voltage Supply2 months ago
    Negative Voltage Supply

    Only power supplies with outputs truly floating with respect to the AC line power (such as this battery operated one) are able to have either terminal connected to ground. Many switching supply converters getting their power from 110 VAC have one of their output terminals (usually the negative) tied to the 3rd wire ground for safety purposes. If you then ground the positive terminal to try to get an output negative with respect to ground you will short out the supply.

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  • bardenbob commented on millmore's instructable Bike Overtaking Distance Sensor11 months ago
    Bike Overtaking Distance Sensor

    Could you please comment on the performance of your TOF sensor when used in the sunshine. Your video shows it being used in overcast or dark conditions - car headlights are on. I tried to use a similar unit (different break out board) in a project. It worked well inside but it seemed to be saturated by the sunlight outside. As a result I had to abandon the project. Thanks.

    I did try a shroud as well as a crude dark glass lens to reduce the intensity. Unfortunately neither approach seemed to help.

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  • bardenbob commented on tpsully's instructable Radar Glasses1 year ago
    Radar Glasses

    I too had variable vibration levels which changed as a function of distance. Closer objects were "louder" and had a shorter rep rate (think torpedo approaching a target). I'm not all that familiar with cell phone vibration motors but I decided to be safe and add a reverse connected diode across the motor terminals similar to what you see used with relay coils. If there's some inductive kick-back it could prevent a latent failure.

    We must be on the same wavelength because I too used a toilet paper roll. If I had gotten any improvement I would have tried painting the inside flat black but alas... The parts I bought came from China so they could have been knock offs or STM floor sweepings but they seemed to conform to the Sparkfun library. I'm guessing they didn't perform much worse than yours. As for the sonar sensors, I didn't think they'd be directional enough and more importantly, they are too large for what I was envisioning. My daughter works with blind people and thinks that if the device is large or ugly they won't be used. The electronics I planned on using were small enough to fit under the brim of a baseball cap or in a cell phone arm band holder. It's too bad there isn't a programmable attenuator on the...

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    We must be on the same wavelength because I too used a toilet paper roll. If I had gotten any improvement I would have tried painting the inside flat black but alas... The parts I bought came from China so they could have been knock offs or STM floor sweepings but they seemed to conform to the Sparkfun library. I'm guessing they didn't perform much worse than yours. As for the sonar sensors, I didn't think they'd be directional enough and more importantly, they are too large for what I was envisioning. My daughter works with blind people and thinks that if the device is large or ugly they won't be used. The electronics I planned on using were small enough to fit under the brim of a baseball cap or in a cell phone arm band holder. It's too bad there isn't a programmable attenuator on the front end of the receiver portion of the sensor. That might keep it out of saturation although it would reduce the range. At least it might work somewhat.

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