Search results

  1. M

    Most inexpensive method for detecting if some current is flowing in 120VAC or 240VAC PCB Trace

    Hello, I am trying to figure out what is the most inexpensive method for detecting if current is flowing in a 120VAC or 240VAC PCB trace. I came across the ACS730, however this gives me the exact current that is flowing, and they are expensive. A simple yes or no would be preferable and I would...
  2. M

    nRF24L01+ PA LNA - Seems that the PA (power amplification) portion of the module is failing?

    There is only a single ground pin on the module (far left pin in the image) and that is it. These are failing at QC... they have not even had the chance to be used yet.
  3. M

    nRF24L01+ PA LNA - Seems that the PA (power amplification) portion of the module is failing?

    I have some good news. I decided to test the RF modules grounding, so I scraped off a patch of the RF modules black solder mask near the PA and connected an additional bridge to the circuit boards ground. Sure enough this fixes it. I’ve done this to two of them so far… both didn’t work before...
  4. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    I just watched a video that explains the noise thing between analog and digital scopes, and how to get a better picture, worth the watch if you use scopes. It looks like this is what I was experiencing:
  5. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    I started questioning this today actually... kind of seems like I'm not. Its a Rigol DS2202A for reference. I will try connecting the ground clip to the probe tip. I did not put capacitors on the 7805, but there is a 100uF capacitor at the input of the PCB where I spliced the wires in.
  6. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    Nope, everything is inside the box. Including the antenna (its a chip antenna on the PCB). It controls a wall outlet. So you plug this device into the wall, you then plug whatever you want into this device, and then you can control it via RF. There are no switches or antennas or anything, just a...
  7. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    Yeah it does look like 1/2 wave now that I look at it. I wonder why the datasheet doesn't mention this stuff? The switcher chip works by skipping the pulses, and this is the only configuration in the datasheet, so wouldn't providing it double the waves mess something up? After some googling it...
  8. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    Sorry Steve, here is the datasheet: http://www.mouser.com/ds/2/328/lnk302_304-306-179954.pdf
  9. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    This is actually a full wave rectification power setup. For D4, are you wondering why its in that location? Or why its in the design period? I just followed the datasheet for the lnk304/305/306 and researched all of the requirements for the parts it recommended (assuming I did it correctly...
  10. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    Don't worry Dave, I did my homework on this and its ok... this device is completely sealed inside an enclosure with absolutely no interface to the outside world... its completely sealed, no buttons no nothing. I also incorporated the fuse and wire-wound resistor as additional safety recommended...
  11. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    Hi Steve, I did design the SMPS, here is the schematic and layout of it: U$2 is LNK305 C6, C7 is this part number: 475CKE450MLN C8 is this part number: 35ZLH100MEFC6.3X11 Thanks again for your help!
  12. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    I took a new board without the RC modification, completely severed the circuit between C8 and R4, rigged up a 7805 and a power adapter. Here are the results: https://goo.gl/photos/U3rpHXU7YF95NMjt5 I now replaced the power adapter with a 9 volt battery: https://goo.gl/photos/gFQuckUUTys6Pyzo9...
  13. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    Hi Steve, thanks for the response! I have actually already tried this. This morning I tried splicing in an RC filter on the 5V rail, and here are the results (not much difference): BEFORE: Video of oscilloscope: https://goo.gl/photos/TxpybHEWfKQrqGRp7 https://goo.gl/photos/h5W5WoXW97UWjsgS8...
  14. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    Thanks for the info, I will check out those pages. Yeah I thought 30mV was pretty small too. This is for a nRF24L01+ module. I spoke to the engineers of some of the modules, and they said that the power input ripple voltage cannot exceed 30mV or else the transmission will not work. When I...
  15. M

    Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

    Hey guys, I have a 3.3 volt DC power rail. I have an integrated circuit that can only operate correctly if its power input has less than 30mV ripple. What is the procedure for building the corresponding filter circuitry to accommodate those requirements? Is there a reading I can take with the...
  16. M

    nRF24L01+ PA LNA - Seems that the PA (power amplification) portion of the module is failing?

    Hi Chris thanks for the response! Here is another design that uses that recommended 1uF output capacitor on the MCP1700, and then a 220uF bulk capacitor. I think the concern is for power down protection correct? At which point a protection diode can be placed across IN & OUT pin of the...
  17. M

    nRF24L01+ PA LNA - Seems that the PA (power amplification) portion of the module is failing?

    Hey guys, I have designed several circuits all of which use a nRF24L01+ PA LNA module (picture of it below). Occasionally we would come across a problem where the module will only transmit when you touch the module or antenna with your finger. This generally means that the transmission is...
  18. M

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

    Hey Sunny, sorry for the late response I missed the notification on the topic. To answer your question. U$3 is that large yellow box outline, its the CO2 sensor mounted to the PCB in the right/middle area. And yes, the 0-2.5V analog out matches the PWM.
  19. M

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

    At one point someone thought that an external device (AC compressor) was triggering the event to occure. We were never able to reproduce anything. Lights turning off and on right next to it, fans on/off, nothing seems to correlate to the behavior starting and stopping. What do you mean by the...
  20. M

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

    Thanks again for the input. Yeah I was certain that the new clean power supply would fix the issue, then I would know it was due to noise... but it didn't help. I also disconnected the 12vdc fan to further reduce noise and rule our... still did not help. The cheap 12vdc power supplies wire...
Top