Search found 54 matches

by thankyou
Mon Nov 23, 2015 9:49 pm
Forum: PCB Design Questions
Topic: MEMS microphone not working on my board
Replies: 1
Views: 898

MEMS microphone not working on my board

I am using the same MEMS microphone that Sparkfun uses in its MEMS microphone breakout board: https://www.sparkfun.com/products/9868 This is the MEMS microphone datasheet: http://www.invensense.com/wp-content/uploads/2015/02/INMP401.pdf For some reason I'm getting no AC output signal from the microp...
by thankyou
Tue Aug 25, 2015 10:05 pm
Forum: Projects
Topic: electret microphone amplifier layout question
Replies: 2
Views: 222

Re: electret microphone amplifier layout question

Ok, thanks for the reality check! The microphone signal is not very responsive to sound, it only fluctuates slightly when I play music or talk. The Sparkfun microphone signal has a better response. I'm not using the exact same microphone, but it is being supplied with the 3V it needs. I'm going to r...
by thankyou
Tue Aug 25, 2015 9:48 pm
Forum: Projects
Topic: electret microphone amplifier layout question
Replies: 2
Views: 222

electret microphone amplifier layout question

I replicated the Sparkfun electret microphone breakout board circuit (https://www.sparkfun.com/products/9964) on a fabricated board, and I'm not getting a good microphone signal. Could there be an issue if the amplifier circuit is too close to the microphone? On the Sparkfun board, the amplifier cir...
by thankyou
Thu Jul 09, 2015 5:01 pm
Forum: SparkFun Product Questions
Topic: DAC MCP4725 question
Replies: 0
Views: 231

DAC MCP4725 question

I used the Sparkfun breakout board for the MCP4725: https://www.sparkfun.com/products/12918 On the schematic, it shows a 10k pull-down resistor from A0 to Ground. A0 is an address selection pin. But on the MCP4725 datasheet (https://cdn.sparkfun.com/datasheets/BreakoutBoards/MCP4725_2009.pdf), it ha...
by thankyou
Mon Jun 08, 2015 2:23 pm
Forum: SparkFun Product Questions
Topic: Questions about LiPower Boost Converter
Replies: 0
Views: 206

Questions about LiPower Boost Converter

I'm using this: https://www.sparkfun.com/products/10255?gclid=CKXHiun2gMYCFUZgfgodAHIAmA Why is this called a booster instead of a buck/boost converter? The datasheet (https://www.sparkfun.com/datasheets/Prototyping/tps61200.pdf) also refers to it in the headline as a boost converter even though it ...
by thankyou
Tue May 26, 2015 9:24 pm
Forum: Projects
Topic: 3.3V regulator with lithium ion coin cell battery
Replies: 7
Views: 956

Re: 3.3V regulator with lithium ion coin cell battery

I think I found the best solution:
http://www.st.com/st-web-ui/static/acti ... 085223.pdf

It's a lithium ion battery charger that incorporates an LDO 3.1V regulator with battery protection circuitry, including over-discharge.
by thankyou
Tue May 26, 2015 2:02 pm
Forum: Projects
Topic: 3.3V regulator with lithium ion coin cell battery
Replies: 7
Views: 956

Re: 3.3V regulator with lithium ion coin cell battery

I'm using an Attiny84 that has an internal 1.1V voltage reference, so I can't power a circuit that requires 3V. Why would a voltage reference be better than using a voltage regulator? I looked up voltage references and it looks like it would either be a Zener diode or a "bandgap" voltage reference. ...
by thankyou
Tue May 26, 2015 12:47 pm
Forum: Projects
Topic: 3.3V regulator with lithium ion coin cell battery
Replies: 7
Views: 956

Re: 3.3V regulator with lithium ion coin cell battery

How would you use a voltage reference that doesn't come from the supply? I don't want a second voltage supply.

Also, I read that you shouldn't use the lithium ion LIR2450 below 2.75V. How would you cut off the voltage?
by thankyou
Tue May 26, 2015 10:49 am
Forum: Projects
Topic: 3.3V regulator with lithium ion coin cell battery
Replies: 7
Views: 956

Re: 3.3V regulator with lithium ion coin cell battery

I need the supply voltage to be stable at the same value while the application is running. This is because I'm comparing analog input voltages (that are based off of the supply voltage) to threshold voltage values in the microcontroller, so I don't want the input voltages to change if the battery vo...
by thankyou
Mon May 25, 2015 4:42 pm
Forum: Projects
Topic: 3.3V regulator with lithium ion coin cell battery
Replies: 7
Views: 956

3.3V regulator with lithium ion coin cell battery

I want to use a cheap 3.3V regulator in my project that uses an LIR2450 3.6V lithium ion coin cell battery. I noticed there are many buck/boost +3.3V switching regulators specifically for lithium ion batteries. I would prefer using an LDO linear 3.3V regulator for the lower cost and not having to us...
by thankyou
Tue May 19, 2015 3:43 pm
Forum: AVR Microcontrollers
Topic: Why is Attiny85 so popular?
Replies: 22
Views: 5542

Re: Why is Attiny85 so popular?

Haha, thank you for the info...I had actually only ever heard of a rising/falling/pin change interrupt, and so it's useful for future projects to know about a built-in analog comparator that can cause an interrupt. Unfortunately for this project, the thresholds change based on user input :(
by thankyou
Tue May 19, 2015 2:14 pm
Forum: AVR Microcontrollers
Topic: Why is Attiny85 so popular?
Replies: 22
Views: 5542

Re: Why is Attiny85 so popular?

Ok, so the analog comparator would be good for using a fixed threshold voltage of comparison, but wouldn't help in the case of a threshold that dynamically changes in code.
by thankyou
Tue May 19, 2015 12:44 pm
Forum: AVR Microcontrollers
Topic: Why is Attiny85 so popular?
Replies: 22
Views: 5542

Re: Why is Attiny85 so popular?

I didn't mean "precise moment" literally, a couple hundred microseconds would suffice. I don't think a comparator would be good because the analog comparison value is modified digitally (the code does a calculation), and if I wanted to output to a comparator I would need to use a DAC, so I don't thi...
by thankyou
Tue May 19, 2015 11:53 am
Forum: AVR Microcontrollers
Topic: Why is Attiny85 so popular?
Replies: 22
Views: 5542

Re: Why is Attiny85 so popular?

I'm using the ADC to read an analog distance sensor value, and I want an action to occur at the precise moment the analog reading is above a value (this value can be modified by the user, so I wouldn't want to use a comparator).
by thankyou
Tue May 19, 2015 12:13 am
Forum: AVR Microcontrollers
Topic: Why is Attiny85 so popular?
Replies: 22
Views: 5542

Re: Why is Attiny85 so popular?

I'm monitoring something with the ADC that can change at any moment, so I do have to read from the ADC constantly...I better read up on programming Attiny43U :)