#1097

This is the first set of tests, carried out using +5VDC powering an Adafruit BMP280, over 6" and 6 FOOT wires (see explanation inside) -- against a 7 MHz 50 watt ham transmitter with an antenna right outside the window, and tested against? a 4 watt ham 2 meter tansceiver with me holding the cable in one hand, the handitalkie in the other and holding the handitalkie about 1 foot from the cable.? ? The results of this level of testing appear very reassuring.??

Next test will move to testing it running on 3.3V from Dr. Stapleton's Nano, which has resistor pullups to 3.3V.? ?Stay tuned.
Gordon

#1099

OK,? the tests above were with 5.0 VDC feeding the Adafruit board (which has level shifters built in)

Now I test using 3.3VDC to feed the Adafruit board (still using the level shifters)? ?Attached see additional testing lines.
even LESS effect, folks!

Next is to see if I can get this to work from Dr. Stapleton's completed Board, which uses Ashar's v0.1 schematic (3.3V pullups, no level shifters; remember the adafruit boad has level shifters on it)

Gordon

BMPWiringAndTesting.pdf

K9HZ

#1101

开云体育

The connection is low enough impedance where it should not matter.? Twist the wires helps with common mode rejection.

?

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

Like us on Facebook!

?

Moderator – North American QRO Group at Groups.IO.

?

email:? bill@...

?

Show quoted text

From: [email protected] [mailto:[email protected]] On Behalf Of Gordon Gibby
Sent: Friday, April 3, 2020 10:56 AM
To: [email protected]
Subject: [VentilatorDevelopers] Testing I2C connection to BMP280

?

This is the first set of tests, carried out using +5VDC powering an Adafruit BMP280, over 6" and 6 FOOT wires (see explanation inside) -- against a 7 MHz 50 watt ham transmitter with an antenna right outside the window, and tested against? a 4 watt ham 2 meter tansceiver with me holding the cable in one hand, the handitalkie in the other and holding the handitalkie about 1 foot from the cable.? ? The results of this level of testing appear very reassuring.??

Next test will move to testing it running on 3.3V from Dr. Stapleton's Nano, which has resistor pullups to 3.3V.? ?Stay tuned.
Gordon

Virus-free.

#1121

Final test -- shows NO INTERFERENCE TO THE 6 FOOT CABLE AT ALL.??

BMPWiringAndTesting.pdf

I2CTestPhoto1Apri32020.JPG

I2CTestPhoto2Apr32020.jpg

#1124

Ferrite beads?

Show quoted text

On Fri, Apr 3, 2020 at 2:33 PM Gordon Gibby <docvacuumtubes@...> wrote:

Final test -- shows NO INTERFERENCE TO THE 6 FOOT CABLE AT ALL.??

#1125

Not even used.? WORKS FINE.? Absolutely bullet proof in those tests.? Astoundingly good.? ?You can walk upstairs with it and see the altitude change -- crank up a high field RF right beside it -- nothing.

Show quoted text

On Fri, Apr 3, 2020 at 2:53 PM KD2QMZ <syracusepro@...> wrote:

Ferrite beads?

On Fri, Apr 3, 2020 at 2:33 PM Gordon Gibby <docvacuumtubes@...> wrote:
Final test -- shows NO INTERFERENCE TO THE 6 FOOT CABLE AT ALL.??