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  1. M

    Troubleshooting MH-Z14 CO2 Sensor Output Connected To Microcontroller - Sometimes readings go crazy

    Here is a video of the 5V rail right up next to the MH-Z14 sensor (using the cheap chinese 12vdc power adaptors we have been using): https://goo.gl/photos/KEVMEQLgyUst7jeBA I tried a different 12vdc power adaptor and here is what the 5V rail looks like: https://goo.gl/photos/MBckLNoGTdXnzw3K8
  2. M

    Troubleshooting MH-Z14 CO2 Sensor Output Connected To Microcontroller - Sometimes readings go crazy

    Thanks for taking a look. So you think there may be too much noise on the 5V power input going to the sensor and I should attempt to filter it more? I already have bypassing capacitors on the power line right next to sensor input (1uF and 0.1uF). How would you recommend filtering the power...
  3. M

    Troubleshooting MH-Z14 CO2 Sensor Output Connected To Microcontroller - Sometimes readings go crazy

    Its not an audio connector, Its a standard barrel connector that is on most dc power supplier - like this:
  4. M

    Troubleshooting MH-Z14 CO2 Sensor Output Connected To Microcontroller - Sometimes readings go crazy

    Hey guys, I have some MH-Z14 CO2 sensors connected up to a Particle Photon microcontroller. Its a relatively simple circuit consisting of a 12vdc wall wort as power input, a 5v voltage regulator (RECOM R-78E5.0-1.0), a couple sensors, and a 12VDC fan. I have a bunch of these devices running in...
  5. M

    Built circuit w/ timer IC connected to SHDN pin of a voltage regulator - not shutting down properly?

    I built a PCB with only the MAX1795, the input capacitor & inductor, the 2 output capacitors, and a 100 ohm resistor for a load. Like this the thing works perfectly. I get 40mA current draw when SHDN is grounded, and when I connect SHDN to battery I get only 0.01mA current draw. This was with...
  6. M

    DS18B20 Temp Sensor - Working Intermittently & Not Reliable - Took Scope Readings & Could Use Advice

    Hey guys, I am using a Particle Photon (microcontroller w/ cloud connectivity) to communicate with a DS18B20 temperature sensor via the 1-wire bus. Below is how I have it wired up: From the research I have done, it seems to be preferred that you use 5 volts to power the sensor, then a pullup...
  7. M

    Built circuit w/ timer IC connected to SHDN pin of a voltage regulator - not shutting down properly?

    Ok I de-soldered the IC1 (R-78E3) to remove that from the equation and nothing changed. Still getting about 5mA when shutdown mode is enabled. FYI, I am taking the current reading at the batteries. However... I tried with only a single battery and the thing now works. These batteries are AA...
  8. M

    Built circuit w/ timer IC connected to SHDN pin of a voltage regulator - not shutting down properly?

    Do you think this means that power is getting drawn from something external? Or is my shutdown circuit malfunctioning?
  9. M

    Built circuit w/ timer IC connected to SHDN pin of a voltage regulator - not shutting down properly?

    Thanks again for all the help! So I re-designed this thing, only using the MAX1795 instead, and an inverter for the SHDN pin since it works the opposite as before. I am still getting a similar problem? When the SHDN pin is pulled low, this enables the MAX1795, and I see the 20mA @ 3.5 volts...
  10. M

    Built circuit w/ timer IC connected to SHDN pin of a voltage regulator - not shutting down properly?

    Maybe this would be a better choise then? NC7SV04P5X Its for a battery powered device with long duration sleep modes. In sleep mode the only thing being powered is the timer IC (TPL5111), the boost regulator (MAX1795 in shutdown mode), and the inverter.
  11. M

    Built circuit w/ timer IC connected to SHDN pin of a voltage regulator - not shutting down properly?

    Thanks for the info. I didn't understand the difference between "shutdown" and "true shutdown", I was comparing so many different boost converters that I assumed the shutdown all worked the same, and missed that piece of the datasheet. So with that in mind, I am thinking I can just use the...
  12. M

    Built circuit w/ timer IC connected to SHDN pin of a voltage regulator - not shutting down properly?

    Hey guys, I built a circuit using a timer IC (TPL5111) connected up to the SHDN pin of a voltage regulator (MAX1724). Here is a simplified schematic of the intended use of the timer IC: The basic idea is that the device powers up, a microcontroller can do a few things, the microcontroller can...
  13. M

    Hot Swapping Headphone Jack - Temporary Shorts During Insertion - How To Remedy?

    My intention was not to take credit, it was simply to get it across that I dremeled out a trace and soldered in a 220 ohm resistor and everything is good. Man you guys are sensitive haha. And I did thank him actually. I was also getting help on "electro-tech" with the exact same solution (220...
  14. M

    Hot Swapping Headphone Jack - Temporary Shorts During Insertion - How To Remedy?

    I was able to solve the problem. All it took was a 220 ohm resistor in the 5V rail and problem solved. During a short, only 22mA will flow, and the resistor will dissipate 0.113 watts: I=V/R I=5/220 I=0.0227 P=VI P=5*0.0227 P=0.113 watts
  15. M

    Hot Swapping Headphone Jack - Temporary Shorts During Insertion - How To Remedy?

    Thanks for the response Dave, But as mentioned above, "Another note: I cannot switch to a different style of plug, it has to be a 3 wire stereo audio jack." Everything has to be these standard audio connectors, so I am looking for a solution that can accommodate them.
  16. M

    Hot Swapping Headphone Jack - Temporary Shorts During Insertion - How To Remedy?

    Hey guys, I have a 3-wire temperature sensor (DS18B20) wired up to a headphone jack. I have the corresponding receptacle on the PCB. If the device is powered off before insertion of the plug, everything is fine. However, inserting the jack while the device is running causes the device to reset...
  17. M

    Power supply circuit question - Transformerless good idea? Still pass certification?

    I need to know why though.
  18. M

    Power supply circuit question - Transformerless good idea? Still pass certification?

    Thanks for the replies, I will do my best to answer all of the questions: 1. Old Steve, I really liked that power supply schematic and something like that would work perfectly. The only problem is I cannot find a transformer with a 24V secondary rated for 35 amps. Well I did find a couple, but...
  19. M

    Power supply circuit question - Transformerless good idea? Still pass certification?

    Hey guys, I am in the process of deciding on a good rout to take for the power supply for my project. I had a couple of questions about it. More info on the device: The device is for home brewing, its a standalone device that sits on the floor, shelf, mounted to a frame, etc. Its actually...
  20. M

    Need help on converting 0-5v signal to 0-10v signal

    Ok I was able to measure the amps by just cutting a spare cable and measuring it from there. The machine draws between 150uA and 10uA (0.15mA and 0.01mA)depending on the potentiometer position (my device is basically going in place of the potentiometer to control the machine). So this is...
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