Tagged Questions
3
votes
1answer
102 views
Are these pcb layouts good?
I'm working on an USB audio interface; the board has an analog section, with amplifiers and filters for the input and the output signals, a digital section, with the DAC, ADC, and the microcontroller ...
0
votes
0answers
53 views
LED display has noise
I am developing a LED display driver. It uses a PIC18F452 microcontroller and a 74hc245 IC.
It uses the SPI protocol to send signals to the LED display. When there are small number of LEDs switched ...
7
votes
2answers
22 views
Does the Arduino Uno “Clean” the power input from the adapter?
I am building a temporary Arduino project, and I need to order an adapter online. I am concerned that, if my adapter has lots of noise, it will affect the Arduino. Since this is temporary, I am going ...
1
vote
1answer
121 views
Shared GND on 2 ATX Power Supplies
I'm constructing a custom(cheap) power supply, with digital current meters and such.
I'm using 2 ATX power supplies to build it. I'm using 1 for the standard -12, -5, +3.3, +5, +12 outputs. I've ...
5
votes
2answers
523 views
What is Power Supply Rejection Ratio and how does a high PSRR help me?
A lot of regulator datasheets give a figure of Power Supply Rejection Ration in decibals. I understand that a high PSRR is good, but how and where does it help me?
For instance, suppose I have a ...
9
votes
1answer
1k views
What might be the cause of high pitch sound coming from a switching regulator circuit
We designed a switching regulator circuit using a 1.5Mhz, internal-switch, switching regulator (semtech.com/images/datasheet/sc185.pdf). Vin is 5V, Vout is 3V3. We have an input capacitor (47uf), an ...
2
votes
3answers
2k views
Ground loop? Switch mode power supply noise
I have a single 12V supply powering a 12V class D audio amplifier (Tripath TA2020 based, model 'SMSL SA-36') (C) and a very cheap 12V to 5V 2A rated switch mode converter (A). The 5V is used to power ...
7
votes
3answers
619 views
Need help with eliminating LED-generated noise
I am very new to electronics, to electronics.SE.com and this is my very first project, so bear with me if my question misses some key-information (in such case, just leave a comment and I will try to ...
3
votes
4answers
874 views
Power Supply Noise
What is a good decent power supply noise?
Let me expand, two cases, I have a bench top PSU, I put my scope in AC coupling and look at the ripple it is around 20mV. Is this a good number for a decent ...
3
votes
3answers
416 views
How to apply passive PFC on low side of transformer in power supply?
I have a low power power supply, built with a 60Hz 120v/12v 0.3A transformer. It will have an ordinary diode bridge and capacitor filter. What I want to achieve is reduction of current/magnetic field ...
3
votes
1answer
584 views
What component of my phone charger produces chirps and how does it do that?
My Nokia cell phone is charged with a very lightweight compact charger similar to this AC-15 (can't find the one I actually use).
While the battery is close to empty the charger works silently - just ...
4
votes
4answers
1k views
Relationship between PSRR and gain
Wikipedia says that power supply rejection ratio (PSRR) is the ratio of output noise referred to the input vs noise at the power supply:
The PSRR is defined as the ratio of the change in supply ...
1
vote
3answers
424 views
Switching Voltage Regulator with WiFi Ethernet Controller Bad?
I a working on a circuit that has components that need 3.3V and 5V. My power input is 12VDC and can not be changed. The 3.3V components use about 510mA of current and the 5V components use about ...
