Counter Idea

[tonedeciple]

bye

Sorry to be a pain, but does this look right based on your schematic?

[-Elepro-]

yes...

the blue wire go to input+ and the green one at input-

bye

[tonedeciple]

yes...

the blue wire go to input+ and the green one at input-

bye

Thank you so much!! It's been a long time since I breadboarded anything so I wanted to check with you first.

Now here's an idea for your CNC winder. It's an automated potting method. With about 60-70% of the wind complete, the winder would slow to about 100rpm. Then, a servo would open a tiny valve and release a drop or two of water-based polyurethane onto the coil. Capillary action would draw in the poly and after a few turns, the winder would return to speed. At the end of the wind, the winder would slow down again to allow another drop or two of poly onto the coil. No more messy wax potting! Here's a simple drawing.

[David King]

For the potting idea I'd suggest wicking the material directly onto the wire as it passes onto the bobbin. That shouldn't be too hard.

[tonedeciple]

I'm about to order my parts, but I found a wall wart rated at 3.0VDC/400mA. What would the new R1 and R2 values be? I realize there are online calculators for this info, but I can't tell from the spec sheets what numbers to plug in.

[-Elepro-]

it seems that 3vdc is not enough for counter input....

[tonedeciple]

it seems that 3vdc is not enough for counter input....

In that case, I'll stick with a 12VDC/100mA.

[MistaT]

One thing I have found with "wall warts" is that all too often the voltage printed on them is all too often not what is actually put out. It seems they are dependent on how much current is drawn from them.

Additionally, most devices that use wall warts have some sort of internal regulating device (zener diode / resistor or something..) because of this condition.

So if the voltage is non-critical, and your circuit can tolerate large voltage swings, then a wal wart is ok. Otherwise I would stick with a "real" power supply that is regulated. They can usually be found pretty cheaply. Near where I live there is an electronic surplus store. I can always pick up a used switcher for around $5 there.

[tonedeciple]

Otherwise I would stick with a "real" power supply that is regulated.

What specifically would I ask for?

I emailed the circuit diagram and counter specs to Fairchild. They said that since we don't know the counter's input current or resistance it may or may not work since the counter may require more than 600uA. We'll see. I ordered two of the QRB1114 sensors just in case. I also got a 12VDC 100mA wall wart for 2 bucks.

[MistaT]

FOr a power supply, basically anything will work. Just ask for a (for example..) 12 volt DC power supply. For a counter, you don't need much current, probably something like 25-50 ma ( 50 ma = 0.050 of an amp) but typically their power supplies will be able to supply much more than that. Basically so long as your power supply has a current rating greater than your needs, and you will be fine.

Now as far as what Fairchild said about their sensor:

The thing to do then. is to place a resistor across the counter input. This will provide a current path with enough current flow for the sensor to work properly. Once the sensor works properly, so will the counter.

This is exactly the problem that I had with my setup. On my counter, I used a 560 ohm resistor. Take a look at the wiring diagram for my counter that I posted earlier.

So in doing the math, (ohms law..) a 560 ohm resistor with a 12 volt supply will draw about 22 ma (0.022 of an amp) so figure that the counter will draw a couple more ma, and this number should not exceed the max. current flow of your sensor.

I just checked the specs of your Fairchild sensor, and the "continuous forward current" is 50 ma, so you sould be ok (again like the Fairchild rep. said, we don't know how much current the counter will pull, but usually they don't pull a lot).

Hope this helps!

[tonedeciple]

On my counter, I used a 560 ohm resistor.

So, perhaps something like this based on Elepro's original schematic?

[MistaT]

Yep!

The 560 ohm resistor is what I am talking about.

[tonedeciple]

Yep!

The 560 ohm resistor is what I am talking about.

Thanks! Should have everything for both the winder and the counter by the end of this week. I will share the results here, on youtube and my web site,

P.S. I bought "Electronics Demystified" yesterday to brush up on the various laws!

[MistaT]

Cool! post a link here if you would for your yourtube video, I would like to see it.

That book you bought, I have heard of it, and I think I flipped through it at the bookstore. IIRC its a good one!

[David King]

Most electronic devices have a + or - 10% voltage compliance. You can put a dummy load across your supply voltage and see what the actual voltage is under load with a meter and then add in a resister in series to get you closer to the rated input voltage for the device. For very brief durations, a few seconds, you can get away with 30% over-voltage and take your measurements directly if you have no idea what the device's supply current is going to be.