>>Optek OPB755TAZ sensor to Red Lion Cub 2 wiring help needed<<

[jack briggs]

Hello all,


I saw a couple of thread where someone was asking for help with the Optek OPB821Z, but I've got a OPB755TAZ.
http://www.optekinc.com/datasheets/OPB755TZ.pdf
The problem is that the sensor requires 2VDC but has 24VDC output to the counter (or 30V - don't know if that looks right.) The Cub 2 counter needs to see 5-6VDC from the sensor.
http://www.redlion.net/Products/Grou...Docs/01006.pdf
I have a 12VDC wall wart for power supply. The resistor calculator that David King referred to shows I need a 120 ohm 2 watt resistor to get 2VDC @ 100 mA supply for the sensor LED. I understand that the Cub 2 is self-powered, but won't the 30V out from the Optek fry the counter?

Help, please!!



Cheers,

[Jazz P Bass]

The output of the OPB755 TAZ is called an open collector.
There is not any voltage on it.
It is open.
The OPB will turn it on & off.
The collector lead gets tied into the counter & pulls it down to the emitter (which is ground).

[jack briggs]

JPB,

Thanks for the reply. I don't understand why the spec sheet states the collector-emitter voltage at 24V then. Of course, it doesn't make much sense that it would itself produce voltage, but why would this spec be there? I want to be absolutely certain that I don't fry the counter.


Cheers,

[Jazz P Bass]

Where are you getting 24 volts from?
The CUB has it's own battery.
3 volts.
That is what the open collector will pull down as a valid count.
It's the same thing as a reed switch.

[jack briggs]

Where are you getting 24 volts from?

here:
http://www.optekinc.com/datasheets/OPB755TZ.pdf

The CUB has it's own battery.
3 volts.

I know that.

That is what the open collector will pull down as a valid count.
It's the same thing as a reed switch.

Thanks for your comments.

[salvarsan]

The 24V spec is a maximum value, means
"don't hook the fucking OP755 output transistor to more than 24 volts."

The LED side is spec'd for 20ma normal use, 50ma maximum. Do NOT use parts at their maximum spec unless you are drag racing and understand that the lifetime use is drastically shortened

note: 20 ma = 20 milliamps = 0.02 Amps

The OP755 LED's forward voltage drop is 1.8V worst case and determines the resistor value you'll need.

Tutorial on calculating resistors for LED's: Mayothi

Fiddling with Ohm's Law, you get
Resistance = (Voltage - 1.8) / 0.02

The most common DC power supplies are 5,9, and 12 volts.

For 5V, 9V, and 12V, your resistances are
160 ohms, 360 ohms, and 560 ohms respectively.

Thru-Hole mounted resistors are usually labeled in color codes.

160 = brown-blue-brown color code
360 = orange-blue-brown
560 = green-blue-brown

Search Google for more on resistor color codes.

Sincerely,
The Immoderator

[J M Fahey]

Sorry jack briggs, you are understanding your data wrong.
As jpb said:

The output of the OPB755 TAZ is called an open collector.
There is not any voltage on it.
It is open.
The OPB will turn it on & off.
The collector lead gets tied into the counter & pulls it down to the emitter (which is ground).

Means the output works as a switch, by itself produces no voltage but switches what's there.
And like any switch, it has a current and voltage rating which must not be surpassed or it will fail.
In that case, you can never apply more than 24V DC there, that's what the spec means.
Since you are using a 12V wall wart (which in practice will mean anything up to 16V unloaded), you'll be fine.
PS: and 100mA for a LED is too much.
I'd use 30 mA ; definitely 50mA tops.
If possible, stuff must not be pushed to the edge.

EDIT: Oooops !! Simulposting !!
Although, as you see, we agree (which is reassuring)

[Jazz P Bass]

I don't think the OP 'gets' open collector.

[jack briggs]

Sorry jack briggs, you are understanding your data wrong.
As jpb said:

Means the output works as a switch, by itself produces no voltage but switches what's there.
And like any switch, it has a current and voltage rating which must not be surpassed or it will fail.
In that case, you can never apply more than 24V DC there, that's what the spec means.
Since you are using a 12V wall wart (which in practice will mean anything up to 16V unloaded), you'll be fine.
PS: and 100mA for a LED is too much.
I'd use 30 mA ; definitely 50mA tops.
If possible, stuff must not be pushed to the edge.

EDIT: Oooops !! Simulposting !!
Although, as you see, we agree (which is reassuring)

Thanks - got it.

The 24V spec is a maximum value, means
"don't hook the fucking OP755 output transistor to more than 24 volts."

The LED side is spec'd for 20ma normal use, 50ma maximum. Do NOT use parts at their maximum spec unless you are drag racing and understand that the lifetime use is drastically shortened

note: 20 ma = 20 milliamps = 0.02 Amps

The OP755 LED's forward voltage drop is 1.8V worst case and determines the resistor value you'll need.

Tutorial on calculating resistors for LED's: Mayothi

Fiddling with Ohm's Law, you get
Resistance = (Voltage - 1.8) / 0.02

The most common DC power supplies are 5,9, and 12 volts.

For 5V, 9V, and 12V, your resistances are
160 ohms, 360 ohms, and 560 ohms respectively.

Thru-Hole mounted resistors are usually labeled in color codes.

160 = brown-blue-brown color code
360 = orange-blue-brown
560 = green-blue-brown

Search Google for more on resistor color codes.

Sincerely,
The Immoderator

I don't think the OP 'gets' open collector.

Such a warm and friendly bunch here.

Although I was wiring amp kits and dabbling in electronics in the early 1970's, I have no degree in it (obviously). What has happened to asking and getting help in understanding something without condescending replies, huh? Are you guys so bored that the only fun you get is ridiculing someone with less knowledge at something than you? What the hell is a forum for, anyhow, if someone can't ask for and expect a little help? This kind of attitude is why I've been absent from this forum for the majority of the last 2 years.


Cheers,

[RedHouse]

Oh Jack, don't take it like that, Salvarsen just has a particular style of posting.

If you are a "sensitive guy" just skip past his humor (ok, sarcasm) and look for the gems, he'll always post valuable answers for ya.
(personally, I like his sarcasm but YMMV)

When I read his post above, I merely associated it with the old acronym "RTFM" which is commonly used in technical peer-2-peer discussions.

I have a diagram somewhere (I need to look for it) that shows how to hook up a CUB to an Optek, I'll try to find it and post a link here tomorrow (it's 3:35am, I'm tired)

[RedHouse]

(darn double posts, I wish they'd fix that)

[Jazz P Bass]

I would also like to clear the air.
My remark about 'I don't think the OP 'gets' open collector' was NOT meant to be snide or abusive.
I sincerely thought that the OP did not understand the useage of an open collector circuit.
This is what I believed was the stumbling block to answering the question.
My apologies are offered if my remarks where taken as insultfull.

[jack briggs]

Guys,

Thanks. Your experiences and knowledge in this area are much appreciated!

If I came across as knee-jerkin' and thin skinned, well - that's my bad.

BTW - I got the sensor/counter thang workin' well. After a first wind (P90 soap), I calculated my DCR vs. the # of turns that the counter showed and it seems the sensor is about spot on. With 42 PE single-build (MWS) and 11023 turns I read about 8.98K, which should be about right. I don't think the counter missed or double-counted at all.

I am in the process of getting this winder thing together and will post some pics after a couple trial winds are under the belt.

Thanks again for the help!


Cheers,

[RedHouse]

Oh ok then, well I found the PDF but you don't need it now, in case you do, it's here: http://www.classicamplification.net/...optek-cub4.pdf

It shows a cub4 but 2-5 work fine with it, and other optek sensors.

[J M Fahey]

Congratulations on your success, and yes, that's the atmosphere around here.
No useless insulting answers like in 90% of forums out there, but straight to the point and accurate ones.
Which sometimes, yes, may *sound* somewhat rough , or at least could use some sugarcoating.
And *that's* the "warm and friendly" aspect: getting you answers which help you solve your problem.
If I fall in a river, I'd much prefer a few grumpy old men who pull me out of it, than a bunch of useless people who say "we'll miss you, you "were" our best friend, bye bye"
Oh well.