Modern Device Forum

yoc1983,

I just sent a request to share those images

Paul Badger

yoc1983,

Just check the product page, and also news. I'll post blog posts as soon as I get new regressions done.

Paul

MendipMac , I would advise using a meter to measure the current on the whole setup, then calculating whether your battery is going to be able to support the application for a week. For example if the total current draw is 50 mAH then 50 x 7 x 24 = 8400 mAH AA batteries capacity is in the 2200 mah ra...

yoc1983 I just ran some dummy numbers through that expression and it can't possibly be correct. For the time, you have to wait for better data. If I can find that regression I'll try and rework to find where I went wrong. Usually when I get done with a new regression, I run it backwards with the inp...

MendipMac, I'm not a betting man but I would bet you're going to find that that boost circuit is dragging 3.3V down, so do check that. That is the reference for your ADC so you'll probably need to alter the math. The setup you have is not going to be viable long term, a 9V only provides about 700 mA...

For the zero wind value - use a volt meter and measure the voltage with glass over the sensor, but don't lay the sensor flat against a table, angle it upward so sensor is in air on all sides. Measure the voltage from the temp sensor and run it through the equation VOUT = TC * TA + V0°C The Rev P use...

MendipMac, VOUT = TC * TA + V0°C The Rev P uses MCP9701A temp sensor Where: TA = Ambient Temperature VOUT = Sensor Output Voltage V0°C = Sensor Output Voltage at 0°C + 400 mV (0.400) TC = Temperature Coefficient 19.5 mV/°C (0.0195) I get the same result, hmm Does the sensor respond when you heat it ...

Anchjana,

About what we have on the website is what we've got. We're not happy with it either. We have a new temp controlled wind tunnel and are trying to get it instrumented and automated for new curves.

Paul Badger

Foxbat I've got some 40 gauge from here https://store.coilsociety.com/nifethal-70/40-awg-nifethal-70/500-ft-40-awg-nifethal-70 Seems like a low cost option if it works. If you send me your address a support@ md I'll send you 10 feet of mine or however much you want in an envelope. That according to ...

Foxbat_25BM,

You might look at your power supply, and see how clean that is.
You might also read about ground loops.

(2) Within the balance bridge, which resistor needs matching? In the schematic posted online, I assume it is R3 (2.21 Ohms) The pot trims the 10K reference side of the circuit. I think we'll keep the schematics a step behind actual production. I'm well aware that our products can be produced more c...

Roy,

Yes - maybe email support at moderndevice.com and I'll answer some of the technical questions about where we're at with testing and new regressions. As you mention the listed code is old.

Paul Badger

Roy,

The bridge is R3/R4 R5/R6
As the sensor heats up the bridge is balanced.

Paul

and how did you arrive at the equation Vraw = V0 + b * WindSpeed ^ c. I know in your blog you derived this from an formula done by university of E2 – A2 = B U0.5. can i have the name or reference to the university white paper that you read about. Caimbridge University in UK has lots of great inform...

rynait r5 & r6 are setting a reference voltage to be compared the active arm of the circuit. When the voltage changes the heated sensor changes resistance, balancing the circuit. So voltage is proportional to the square of wind speed, approximately. R5 representing a small value in proportion to oth...

rynait, I don't have any special knowledge about this. But some facts about the sensor that may or may not be useful.  • The sensor is pretty easy to spit the sensing head off from the electronics just cut it with tin snips between the headers and then join back together with three wires. Distances ...

abian_B

Glad you got it working. About +- 1.5 degree variation max, is what I see in the shop too, when testing the sensors.

pb

quarterturn, The easiest way to do this is with a serial port that is not attached to the USB such as Serial1 on a Mega. Here's a brief sketch of what I think is the easiest way. • Make sure the Fluxamasynth solder jumper is set to the left hand pad to the middle - right hand pad is bare (not connec...

The temp sensor is MCP9701A. Its output is not scaled at all. Tambient = ( Vout*(5/1024) – 0.400 ) / 0.0195 should be correct if Vout is the read from the analog pin ADC on a 5 volt arduino. Recheck pin connections? Test your arduino ADC with a simple voltage divider to see if reads ~512 I'm baffled...

bschulz1701, I don't think we're going to update that schematic. We have been rethinking whether we even want the wind sensors to be open source at all, since they're unique products and we have spent a lot of time figuring out the circuits and getting them calibrated in their current state. We cont...