Measuring how dirty the power is

Wall wart probably no good, use a good regulated power supply.

Yes, I know that but thats not my question. Im trying to figure out how exactly I can measure just how "dirty" the power is.

Other than measuring the voltage and seeing if it varies when you try to run you device there is not much you can do with a meter. The most likely cause is that the PS is not capable of supplying the current required. It is unlikely that the power is "dirty". To see "dirty" power you would need an oscilloscope.

Dan H

--- Connect an oscilloscope to the RF device's DC input terminals.

If you see a lot of junk there connect a small aluminum electrolytic capacitor in parallel with about a 0.1µF ceramic from the power supply + terminal to ground. Keep the leads as short as you can. No, two or three inches is _not_ short enough.

If that doesn't work, post back and we'll try something else.

BTW, I've crossposted this to sci.electronics.design, where there's a lot of talent.

Also BTW, _Please_ bottom post. :-)

-- John Fields Professional Circuit Designer

^ device's

I figured this but I do not currently have access to a scope nor the funds for one. I was hoping their was some kinda trick to get what I needed off a meter.

Thanks,

Bryan

Voltage has remained stable. I have also attempted to place a 10ohm resistor in series with the supply along with a 10uf compacitor from VSS to ground to try to clean it up but that didnt work either. In the data sheet it says I need to keep the noise and "hash" below 20mV for which I was trying to see how I could see the 20mV without a scope.

I am using a 12volt DC power supply which hits a voltage regulator to knock the voltage down to 5V for the module. I have tested this with no other components other that the transmitter/recv'er and also by using the above reference to try to clean it up all w/out success. Voltage stays consistant from power up and during transmit. Can you think of anything else?

Well you could try switching the meter to AC and see if you read anything both at the 12V and 5V point. If it is ripple the regulator should take care of it but if it is spikes they may be passing thru regulator. Try some capacitance on both the input and output of the regulator. Also check you grounding. how far apart are the devices?

It is really tough to solve this kind of problem without knowing what is really going on.

Dan H

Quick, easy and yet somewhat reliable: Connect a crystal-type earphone with a 0.1 uF capacitor in series across the DC powerline. If there is noise in the audio range, you will be able to hear it.

Note: this can only be done with a crystal type earphone.