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Products => Test Equipment => Topic started by: LIGHTSSOUT on August 14, 2015, 07:51:39 am

Title: 72-8355 TENMA Power Supply Noise
Post by: LIGHTSSOUT on August 14, 2015, 07:51:39 am

Hi

Can anyone give me advise on Power supply noise.
I brought TENMA 72-8355 and when I probe my circuit board with an analogue discovery on the output of a MOSFET I have noise on the PWM signal.
See attached picture.
The noise also goes away when connected to my PC's USB

First time using an Oscilloscope so please be nice :)

Thanks in advance for any help

Title: Re: 72-8355 TENMA Power Supply Noise
Post by: TheAmmoniacal on August 14, 2015, 08:01:32 am

Is the power supply not working as it should? "noise" on switching signals or PWMs are rarely a problem. And why are you probing a MOSFET?

Title: Re: 72-8355 TENMA Power Supply Noise
Post by: LIGHTSSOUT on August 14, 2015, 08:13:55 am

Quote from: TheAmmoniacal on August 14, 2015, 08:01:32 am

Is the power supply not working as it should? "noise" on switching signals or PWMs are rarely a problem. And why are you probing a MOSFET?

Just learning, the Mosfet is needed in the circuit as the Micro I am using can not source enough current to light a multiplexed LED display.
I am using a PSOC4 BLE from cypress on there development kit.

All other parts are OK and are Square

Title: Re: 72-8355 TENMA Power Supply Noise
Post by: LIGHTSSOUT on August 20, 2015, 09:50:30 am

Just an update.
Found out that the Pins are/have to be left floating on the multiplexed display.
So nothing was wrong. ^-^