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Re: MPU9250 - how to change address?

 by madbodger ¦  Sun Jul 01, 2018 7:42 am ¦  Forum: Arduino ¦  Topic: MPU9250 - how to change address? ¦  Replies: 1 ¦  Views: 368

I suspect that device only reads the AD0 line at power up, so if you change it afterward, the address won't change. Have you tried tying AD0 to 3.3V and then power cycling it?

Re: Adult beginner electronic kit suggestions

 by madbodger ¦  Sun Jul 01, 2018 7:18 am ¦  Forum: Projects ¦  Topic: Adult beginner electronic kit suggestions ¦  Replies: 1 ¦  Views: 276

There are a few ways to get into lighting. A good start is with LEDs, which are cheap, easy to use, and safe (low voltage). An ordinary Arduino style board comes with an on-board LED you can turn on and off (this is how a lot of people get started). After that, you can add external LEDs (along with ...

Re: RFID Counter

 by madbodger ¦  Thu Jun 21, 2018 1:44 pm ¦  Forum: Projects ¦  Topic: RFID Counter ¦  Replies: 2 ¦  Views: 327

Which RFID reader? SparkFun offers a few different options. It's possible that there's a "card detected" sort of output you could use.

Re: reusing TV's momentary pushbotton PCB. Two wire

 by madbodger ¦  Wed Jun 20, 2018 7:18 pm ¦  Forum: Projects ¦  Topic: reusing TV's momentary pushbotton PCB. Two wire ¦  Replies: 1 ¦  Views: 216

It looks like a resistive divider chain, where the switches shunt the resistors in various patterns. The idea is that if none of the switches are pressed, it presents a certain resistance (possibly infinite), and pressing the switches changes that resistance in various ways (likely making it lower)....

Re: hide display on large digit driver

 by madbodger ¦  Wed Jun 20, 2018 7:12 pm ¦  Forum: Projects ¦  Topic: hide display on large digit driver ¦  Replies: 1 ¦  Views: 215

That's known as "leading zero blanking". Normally when I do this, I go the other way (high digits to low digits), and have a blanking flag that starts as "true" and is set to "false" when I encounter the first non-zero digit or get to the last digit (so as not to blank the entire display). When disp...

Re: How does BZX84C7V5 work

 by madbodger ¦  Wed Jun 20, 2018 7:02 pm ¦  Forum: Projects ¦  Topic: How does BZX84C7V5 work ¦  Replies: 0 ¦  Views: 189

The problem is that zeners aren't an ideal device, the graph of voltage versus current doesn't make a sharp, right-angle corner: the voltage rises with current until it approaches the rated current, at which point (known as the "knee"), it curves over into the constant voltage region, where the volt...

Re: Anyone tried CircuitHub or Macrofab?

 by madbodger ¦  Wed Jun 20, 2018 6:41 pm ¦  Forum: PCB Design Questions ¦  Topic: Anyone tried CircuitHub or Macrofab? ¦  Replies: 7 ¦  Views: 2742

I've used CircuitHub, letting them make the boards, source most of the parts, and do assembly. They're not cheap, but they're willing to work with me on issues, and generally do top-drawer work.

Re: voltage divider / rectifier / voltmeter / ESP8266

 by madbodger ¦  Wed Jun 20, 2018 6:35 pm ¦  Forum: PCB Design Questions ¦  Topic: voltage divider / rectifier / voltmeter / ESP8266 ¦  Replies: 1 ¦  Views: 435

Hooking a 120VAC signal to a logic input is tricky. For one thing, you have to pay attention to the peak voltage, which is about 170V. Using your divider, with its 133:1 ratio, that would give about 1.3V out peak. You said you want to use 2 diodes to get AC, I'm assuming you meant DC? I'm not quite ...

SparkFun credit card?

 by madbodger ¦  Sun Feb 13, 2011 6:41 pm ¦  Forum: New Product Ideas ¦  Topic: SparkFun credit card? ¦  Replies: 0 ¦  Views: 603

I'm tired of credit cards with rewards I can't ever use for some reason or another. I don't know how the banks handle it, but
I'd get a SparkFun credit card in an instant if it earned credit at SparkFun! Ideally, the bank would give SparkFun a cut everytime
the card got used.