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Luke55
10-04-2011, 11:35 AM
I want to put a time delay (0 to 4 sec ) in the circuit of a fork optical sensor.
No writhing on it. About 1 square inch half inch thick. It operate on 24VDC wire Yellow and brown wired together. also a blue and a red wire.

Chris S.
10-04-2011, 11:52 AM
Do you want to build this or buy a pre-made board? If you want to build it you can use a 555 chip. If you want most of the work done for you, you can go to Sparkfun.

http://www.sparkfun.com/products/9439

Chris S.
10-04-2011, 12:03 PM
Here's a 555 video.
http://www.youtube.com/watch?v=qwPtSkWyjWc&feature=player_embedded

Scottike
10-04-2011, 12:19 PM
Something like this?
http://www.newark.com/amperite/24d-1-10sst1/time-delay-relay-spst-no-10sec/dp/93B0659

Luke55
10-04-2011, 07:38 PM
many thanks for replyes

Evan
10-04-2011, 08:18 PM
Not so fast with the 555. This is a 24 volt part and if it switches the 24 volt signal (less sensitive to noise) then it will fry the 555 without some signal conditioning.

The yellow/brown are probably -24 vdc, the red is probably +24 and the blue is probably the signal switched to the -24 (ground). Note I said PROBABLY. To test it hook up a 1000 ohm resistor in series with the + line from the test power supply and then connect as I indicated above. It should work if the connections I gave are correct and if they aren't then it shouldn't fry it. If that doesn't work then reverse the functions of the blue and red.

If it works then measure the high output. If it is greater than 15 volts it must be conditioned before it can be used with a 555 timer circuit.

To do that connect a 2200 ohm resistor in series with the opto output and hook that to a 12 volt zener diode with cathode to ground. The signal across the zener can then be used to switch the pin 4 enable input on the 555 configured as a one shot timer. When pin 4 goes high the 555 starts timing. The 555 must be running on the same voltage as the zener voltage, in this case 12 volts. If the output of the 555 (pin 3) is to be fed to any sort of other digital electronics then make the zener 5 volts and run the 555 on 5 volts too.

If you need to start timing when the output goes low then the output of the Opto will have to be inverted. If that is the case then post back and I or somebody else will describe how to do that with just one transistor and a resistor.

Chris S.
10-04-2011, 10:06 PM
Not so fast with the 555. This is a 24 volt part and if it switches the 24 volt signal (less sensitive to noise) then it will fry the 555 without some signal conditioning.


Evan, prior to switching to uCs I built more 555-556 circuits than I care to remember. Every one of them were different and every one of the circuits required different interfacing. Hey, it's only a chip! The tech has to design a functional circuit around it. The 24V supply isn't an issue either, that's what regulators, like a 7805 or 7812 are for.

FYI, I've never had one of my 555 circuits fail on me. This includes auto, marine and high power RF environments. They just require judicious decoupling..

Chris

Evan
10-04-2011, 10:12 PM
The 24V supply isn't an issue either, that's what regulators, like a 7805 or 7812 are for.

I know that and you know that but does Luke know that or how to deal with it?

Chris S.
10-04-2011, 10:58 PM
I know that and you know that but does Luke know that or how to deal with it?

Not likely, but that's why I asked him if he was looking for a home brew approach or something off the shelf. If he had opted for home brew I would have asked him to join AAC so I could more easily post spiced schematics and walk him through the building and testing process. For certain I'd want much more detailed information from him before embarking down that road.

FYI, I can't imagine why but my guess is that you know what AAC is. ;)

Chris

Evan
10-04-2011, 11:42 PM
If you mean All About Circuits, I have checked out the content but not the forum. I have a pretty complete library on electronics and try to keep up to date, somewhat. It isn't easy though. I spent most of my working life working on electronics, starting with vacuum tubes up to LSI silicon. The part that sucks is that I now play around with surface mount when my eyes are the worst.

Here is a laser cut etch mask for an Allergro stepper driver made on my shop built CNC mill. The board is my design.

http://ixian.ca/pics9/smpcb.jpg

Chris S.
10-05-2011, 09:51 AM
If you mean All About Circuits, I have checked out the content but not the forum. I have a pretty complete library on electronics and try to keep up to date, somewhat. It isn't easy though. I spent most of my working life working on electronics, starting with vacuum tubes up to LSI silicon. The part that sucks is that I now play around with surface mount when my eyes are the worst.

Here is a laser cut etch mask for an Allergro stepper driver made on my shop built CNC mill. The board is my design.


I love coffee but over the years I've discovered that drinking it and soldering SMCs don't mix well. If you drink coffee too here's a tip. Before working with SMT chug down two or three beers, wait about 15 minutes and your good to go. :D Disclaimer: This technique won't do a thing for old eyes!

Very nice work on the laser etching! ;)

Chris

Luke55
10-05-2011, 06:11 PM
Hy guys. you lost me on route I'm not an electronic gourou. Can built with a plan not much The device I want is to retard the movement of a bowling pinner. Made some test.
The blue wire goes down when sensor is trigged. I try an in line timer (Carlo Gavazzi) don't work and too expensive. There's 16 bowling alley.

Evan
10-05-2011, 06:57 PM
So it goes low when the beam is interrupted. What is the sensor going to be connected to? Do you know what sort of signal is expected on the input of pin setter?

Luke55
10-05-2011, 08:57 PM
I try to read voltage on every wires on the sensor dc+ - ac I got nothing. In and out goes to a logic card When sensor is interupted the logic card give signal to an electric actuator. When we unplug the sensor the logic card start the cycle we want to retard this cycle 2 to 4 sec. because it enterfere with the sweep gate sensor When the bottom of one or more pins hit the gate it give false results to the player

Evan
10-05-2011, 09:51 PM
There is a very simple thing you can try. Put a 10 MFD electrolytic capacitor across the sensor output with + to the blue wire and - to the yellow/brown wire. It may work to delay the signal. If it does, the delay can be changed by changing the value. The capacitor should be rated for at least 35 volts.

If it doesn't work try a smaller capacitor, perhaps 1 mfd. If that works then try larger values such as 2.2 mfd or two 1 mfd in parallel. Make sure to observe the polarity.

Chris S.
10-05-2011, 11:21 PM
IMHO, Luke needs to give a heck of a lot more pertinent data before any educated recommendations can be given. First off, it's highly unlikely (but not impossible) that the IR transmitter and receiver are operating with steady state (CW) technology. Secondly, I don't think I'd be working with the IR end of this system. Somewhere in this system a EM Relay or SS Relay or relays are controlling the motor and that's where I'd be looking to tap into.

From what I've read thus far I think you'd be wise to find a professional.

Chris

Evan
10-05-2011, 11:38 PM
Steady state is by far the most common for optical switches. I have boxes full of the things in all sorts of configurations and none are anything complicated such as a modulated beam. If the input has a schmidt trigger (likely) it will work fine with a slowly changing signal.

Chris S.
10-06-2011, 09:44 AM
A modulated beam insures stray or ambient light immunity.

MaxHeadRoom
10-06-2011, 10:50 AM
It is very unusual that there is no make/model on it, unless it has rubbed off?
If there are 16 of them, maybe one will still have a label, maybe on the side mounted down perhaps?
Max.

lwalker
10-06-2011, 01:27 PM
It sounds like you either want to delay the signal the logic card gives to the actuator, or delay the signal the sensor gives the logic card. If you want to delay the output, an off the shelf time delay relay would probably work. If you want to delay the input, we'd need more information on the sensor and what type of signal it produces.

I build stuff like this all the time. If you want to discuss it with me offline, you can send me a private message where it may be easier to give specifics. I'm guessing from what you posted about your electronics knowledge that you may be looking for something pre-assembled rather than Do It Yourself.



I try to read voltage on every wires on the sensor dc+ - ac I got nothing. In and out goes to a logic card When sensor is interupted the logic card give signal to an electric actuator. When we unplug the sensor the logic card start the cycle we want to retard this cycle 2 to 4 sec. because it enterfere with the sweep gate sensor When the bottom of one or more pins hit the gate it give false results to the player

Chris S.
10-07-2011, 09:35 AM
There is a very simple thing you can try. Put a 10 MFD electrolytic capacitor across the sensor output with + to the blue wire and - to the yellow/brown wire. It may work to delay the signal. If it does, the delay can be changed by changing the value. The capacitor should be rated for at least 35 volts.

If it doesn't work try a smaller capacitor, perhaps 1 mfd. If that works then try larger values such as 2.2 mfd or two 1 mfd in parallel. Make sure to observe the polarity.

Considering that the Photo-Emitter Diode will have a limiting resistor on the order of 1K or so, a 10uF cap will produce an RC time constant of only 2mS. To achieve a 7 sec delay the cap would have to be on the order of 100,000uF....Huge!
This is approach is totally impractical.

Evan
10-07-2011, 10:13 PM
If the diode is running on 24 volts as was suggested then the resistor will be around 20 K. The time constant would be about 200ms.

However, that is irrelevant since I suggested putting it on the output, not the emitter. The photo transistor will have a fairly high resistor on the collector but that is also irrelevant since it is the time constant of the phototransistor combined with the capacitor that matters since the low going signal is produced by the transistor turning on. It not only will need to sink the Vcc but also the capacitor charge. It won't be a high current device so the effective "on" resistance will be pretty high.

I also think that the problem may be mechanical bounce since I doubt that the problem was designed in. The capacitor will debounce the signal from the Optical switch.

I worked on similar machinery for decades.

Chris S.
10-07-2011, 10:50 PM
If the diode is running on 24 volts as was suggested then the resistor will be around 20 K. The time constant would be about 200ms.

However, that is irrelevant since I suggested putting it on the output, not the emitter.

I wasn't referring to the emitter of the phototransistor. I was referring to the LED. It's the light emitter in this circuit,.. and no, I don't think the LED limiting resistor will be 20K. At 24V with R=1K, Id would be about 24mA. I could believe 2K to 3.3K but not 20K. That would put the diode current close to Id= 1.2mA. The LED would be barely on.

Edit: See next post.

Chris S.
10-07-2011, 10:55 PM
However, that is irrelevant since I suggested putting it on the output, not the emitter. The photo transistor will have a fairly high resistor on the collector but that is also irrelevant since it is the time constant of the phototransistor combined with the capacitor that matters since the low going signal is produced by the transistor turning on.

Evan, I just re-read this. So, you're saying that he should connect the cap to the Photo-Transistor?

Evan
10-08-2011, 01:20 AM
I was referring to the LED. It's the light emitter in this circuit,

Yeah, I know. I am referring to the phototransistor. If you are concerned that the current pulse will damage the transistor when it switches low, unlikely. The phototransistor can withstand a short pulse many times the rated continuous current. A 10 mfd capacitor charged to 20 volts only contains 2 millijoules of energy which is equal to just 20 milliwatts for 100 milliseconds.

Chris S.
10-08-2011, 12:47 PM
Yeah, I know. I am referring to the phototransistor. If you are concerned that the current pulse will damage the transistor when it switches low, unlikely. The phototransistor can withstand a short pulse many times the rated continuous current. A 10 mfd capacitor charged to 20 volts only contains 2 millijoules of energy which is equal to just 20 milliwatts for 100 milliseconds.

Nah, I'm not concerned about that. PTs can't be driven (Ibe) hard enough from a light source to produce destructive collector current. I just don't think a 10uF between the collector and gnd is going to buy him much. If his PT has an external Base pin he can gain quite a bit of delay. I spiced a 500uF cap, paralleled with a 100K, from the base to gnd using a BPX38 and was able to delay the collector output by 8 seconds. Turn Off time was about 1.2 seconds.

Evan
10-08-2011, 01:05 PM
While it may have a base pin available in the case it isn't brought out. Unfortunately most of the housings are glued together so that opening is a destructive process.

Chris S.
10-08-2011, 01:11 PM
Well, that bites!:D