ebikessf's 2k thermal sensor?

[Joe Perez]

I'm not entirely clear on what you're using for a temp display, however I encountered a similar problem when first connecting an LM35 to the beta version of the new CycleAnalyst 3.

In the CA, there is some voltage bleeding from the throttle input line into the temp sense line due to the way they designed the A/D multiplexer. It was originally designed for use with a NTC thermocouple (which is inherently a current sink) so they never noticed this, but the LM35 can't sink current to ground, so it became a problem. I was seeing indicated temps of around 100 degrees any time I applied throttle.

The solution was relatively simple. I placed a 390 ohm resistor between the LM35's output and ground, which was sufficient to sink the relatively small amount of leakage current and yet not so low as to exceed the LM35's current-source capability. The value does not have to be exactly 390 ohms, but it needs to be close. The LM35 can only source 10ma, so you can't go much lower than 300 ohms without distorting the reading, and yet significantly higher values (eg 1k) weren't enough to drain the leakage current. 390 simply happens to be a common value that I had lying around in my big pile-o-resistors (anything in the 330-470 ohm neighborhood would probably suffice- try to stick to the lower end of that range.)

Give this a shot and see if it fixes the problem.

[auraslip]

I'm sure that explanation will be extremely helpful to someone using the new CA.

I'm using the hkvt though - http://www.hobbyking.com/hobbyking/stor ... oduct=9744

I've tried another unit, so it's not the unit that's bad. It's like the lm35 itself is bad. PITA because they're only a buck, but I have to wait and pay for shipping.

When turned on the white wire is showing 13.07v and the red wire is showing 10.30v - so it's not a dead short. Very weird.

[GCinDC]

Flip the connector.

[auraslip]

Flipped the red and the white connectors and it did the same thing. Bugging the heck out of me.

Does anyone know which lm35 I should order since mouser has 43 of them?
http://www.mouser.com/Sensors/Temperatu ... 35&FS=True

[Joe Perez]

I'm using the hkvt though - http://www.hobbyking.com/hobbyking/stor ... oduct=9744

I understand, I'm just not familiar with that device or its wiring, and I can't find a manual or any other kind of documentation on it anywhere. So I'm wondering whether, internally, it's applying a pullup to the line and expecting ground conduction.

Is there someplace I can see the instruction manual for that device?

Does anyone know which lm35 I should order since mouser has 43 of them?
http://www.mouser.com/Sensors/Temperatu ... 35&FS=True

Electrically, they all mostly do the same thing. They have slightly different tolerance specs, mostly. And we're still in the transition era in which leaded and lead-free devices are both available, so that accounts for some of the duplication.

This one has +/- 1.5° accuracy, in the most compact footprint, without any unnecessary bells and whistles:http://www.mouser.com/ProductDetail/National-Semiconductor-TI/LM35DZ/?qs=QbsRYf82W3EsDJ6nROSwPSCIPq9l3%252b1KfAEJj0kZY5g%3d

[amberwolf]

And many of those listings are for large multiple quantities, if you look in the Quantity column. Like whole tape-reels of them in some cases.

[GCinDC]

guess mine is just an lm35dz:

[Joe Perez]

And many of those listings are for large multiple quantities, if you look in the Quantity column. Like whole tape-reels of them in some cases.

And in different packaging for the different quantities, to fit different automated production machines. So you might have one part which can be purchased:

Loose in a bag
Stacked end-to-end in a plastic tube
Stacked side-by-side in a plastic tube
Taped onto a reel
Taped onto a reel upside-down
(etc)

But long story short, typically the first half the part number describe the part itself, the next few characters are things like tolerance, mil-spec, lead-free status, etc., and then a couple of characters to describe the packaging that the part comes in. For most DIY purposes, only the first half really matters.

[mvly]

So anyone able to get this to work with off the shelf LCD display?

[Stryker16]

So anyone able to get this to work with off the shelf LCD display?

I have a hard time relating Celsius degrees to Fahrenheit. So I compromised and went with an analog meter and then printed out a new scale onto a label and presto...

photo (7) by jakevogt16, on Flickr

[mvly]

I finally got this working. It wasn't easy, but it works.

viewtopic.php?f=3&t=43442

Temperature gauges look fine to me. Now to see if I should shrink and make it much better.