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To follow up, i finally got this working. I believe it was a combination of two things:
1. I was using opamps that didn't support rail-to-rail inputs, thanks betwixt. The TI OPA4342s are working well.
2. I had a short between a via and a resistor pad. Lesson learned: I need more space around...
I tested again last night using only 0-3.3V inputs and something is still wrong. Some channels don't respond, some report wrong values, etc. Maybe I damaged the opamps. The ADC continues to work as expected if I drive its inputs directly.
I ordered new TI OPA4342 opamps which claim rail-to-rail...
That light is actually a rear fog light in the Japanese and Euro markets. In the US it's just a reflector.
I've driven a BRZ on track, great little cars.
In Europe, or at least in Germany, they have a rear fog which is a single red light on the driver's side. It looks like a brake light, but only on one side. From what I understand its the law there to have it on when its foggy out so other cars can see you from behind.
US versions of these cars...
Strangely enough I'm familiar with this mod. Isn't the intent to make the rear fog lights into additional brake lights? That's what the US folks were doing anyway since we don't have rear fogs.
The intent of the diodes is to allow the brake lights to power the fog lights, but prevent the fog...
What application is this for?
I've designed harnesses for airborne and space flight payloads and have never had to do any tests like this. Normally we do NASA-STD-8739.4 which basically says continuity, hi-pot, and IR both before and after installation. Then again, there isn't much water up...
Thanks. Yep, GND and 5V are on planes. It's a four layer board.
Tonight if I have time I'll try putting GND and/or 3.3v into all the channels. This would be within spec for the opamps so should work, right? If not I have other issues.
Ok, here's the full scoop. This project is a digital dashboard/data logger for a car.
This circuit/PCB is an arduino form-factor shield that will plug into an Embedded Artists LPC4088 base board. It might be easiest to read my blog post on it here.
Basically I'm using the EA baseboard and...
I'm not exactly sure if this is what you're after, but I was just reading an MCP601/2/3/4 datasheet and it has an application schematic for a photodiode. Section 4.8.3:
https://ww1.microchip.com/downloads/en/DeviceDoc/21314g.pdf
Thanks again for your insight.
1. I will check this. I'm not using a precision reference as this circuit only has 5V input and I need to measure a potential 5V input with the ADC. (I'm starting to see why this won't work). I do have the ADC VDD and VREF tied to the same 5V supply.
2. I checked...
Additional info:
Right now channel 2 is reading 699 which corresponds to the 0.89V i measure at the ADC input. Here is a trace through the circuit:
5.14V at the jumper and at the opamp positive input.
5.03V at the opamp output and negative input (feedback loop). (why are the two opamp inputs...
Thanks for the response.
I just home and began working on this. I first grounded the input for the last four channels. The first four channels are jumpered to 5V via the jumper shown in the schematic grab.
The RC filter on Channel 1 is removed and bypassed, straight shot from opamp to ADC. The...
In my testing so far, I have connected a basic 10k pot on a bread board (with 5V pull up enabled) as well as no connection relying on just the 5V pullup. In both cases I've sometimes seen it work exactly as expected and I've seen the voltage at the ADC input drop. I also have the last four...
Hi all,
I'm working on a project that requires 8 ADC channels and so am using a Microchip MCP3208.
The first four channels are measuring variably resistive loads (temp/pressure sensors) and so have an optional 5V pullup. I thought I would be clever and use an opamp buffer and an RC filter on...
Hello all,
I'm currently working to create a spice simulation part for a OP-270 dual opamp chip. I'd like the model to include both opamps in the chip, U1A and U1B so that i can properly number my schematic, but still simulate it.
As a test, I created a part based on the basic pspice OP27 part...
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