Infrared Beam Testers

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10/19/2015 Pinball News - First and Free

http://www.pinballnews.com/learn/irtester.html

The Ir Receiver on the left is looking at the beam from the Ir Sender on the right.

OTHER Ir TESTERS

Though other things, such as digital cameras and Ir sensor cards, can be used to“look” at the Infrared beam that is invisible to the naked eye, because you can makeyour own version of the IR sender and receiver that I made for myself, once madethey are constantly available and ready to use. This is not true with the Ir sensor cards. The Ir testers that I use are smaller and a lot less expensive than a videocamera. And they are easier to use than a digital camera. The Ir cards and Ir sensitive cameras can only detect an Ir beam. They cannot send a beam; like the Ir sender.


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USES

I have been repairing pinball machines for over ten years. During those years, therehave been several, if not many, occasions when my little Ir sender and receiver havebeen very useful. One example, previously mentioned, is during the alignment of the“long-shot opto” for “ Mist Multi-Ball ” (Kevin Martin ) on “Dracula ”. The Receiver mayalso be used to test for working Ir remote controls of all types and uses. The Ir sender can be used to check some Ir controlled toys. Use of these testers can savethe time and haste of opening the battery compartments on the devices under test.

ALIGNMENT

During “ Mist Multi-Ball ”, the moving target ball is meant to follow the same path asthe invisible beam from the long shot sender. If both parts of this opto system are notalmost completely parallel, the machine may malfunction or give a random Multi-Ballmode.

http://www.pinball.org/rules/dracula.htmlhttp://www.ipdb.org/search.pl?any=Bram+Stoker%27s+Dracula&sortby=name&searchtype=quickmailto:[email protected]://www.pinball.org/rules/dracula.html


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The Ir Receiver can be used to track and collimate the invisible beam from the long shot sender all the way to its receiver across the entire width of the playfield.

TROUBLESHOOTING

The Ir testers can be used to troubleshoot intermittent Ir Senders and Receivers of WMS ball troughs .

http://marvin3m.com/wpc/index3.htm#trough


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The Ir receiver (transistor) board is on the left and the Ir sender (diode) board is onthe right.

Heat and vibration from normal game play can loosen the dropping resistors and Ir LEDs . When these components get loose the game may give a “ball(s) missing”message at start-up or random Multi-Ball during play.

http://www.pinballnews.com/learn/leds.htmlhttp://www.pinballnews.com/learn/leds.html


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On the left, the visible red LED is lit, indicating presence of the Ir beam from thebottom right Ir LED. On the right, the visible red LED is dark, indicating absence of

the Ir beam from the bottom right Ir LED after I wiggled the lens of that LED.

CIRCUITS

From the following enhanced picture, you can get some idea of how tiny the Ir circuits are. Consider that the picture shows both of the slightly more parts intensiveimproved Ir circuits.


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On the left side, is the circuit for the Ir sender. Here the lit green LED shows that theIr beam is being produced. On the right side, is the circuit for the Ir receiver. And

again, a green glowing LED shows presence of the Ir beam.

I designed two versions of both the Ir sender and the Ir receiver. Both the sender and receiver have basic and improved versions. The improved versions are the onesthat I built to troubleshoot tricky Ir switch problems.

Both the sender and receiver circuits draw only about 5.0mA. So, unless your kidsplay with the testers, you should only need to replace the batteries as you shouldreplace the batteries in your pinball machines; once a year. Even with the tinyamount of current used to run either of the circuits, either can be used from adistance up to about 2.5 feet (about 75 cm).


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Because these little circuits are simple to build, I decided not to provide parts lists.With the exception of the opto parts, the majority of the components are standardvalue parts that should be fairly easy to purchase. All of the parts can be easilyviewed in the following schematics. Each version of the two circuits has its ownschematic.

Though I did not provide parts lists, I did provide parts substitution lists and partssuppliers. I personally recommend Ed of Great Plains Electronics - GPE . Should youdecide to make your own Ir testers, GPE should have the majority of the parts.

PARTS SUBSTITUTIONS

2N3904 Transistor (General Purpose NPN) Substitutions2N44012N5551MPSA06NTE123AP

2N3906 Transistor (General Purpose PNP) Substitutions2N44032N5401MPSA56NTE159

9 Volt Battery By Other NamesPP316046LR619 Volt Cell Battery9 Volt Transistor Battery

Capacitor SubstitutionsThe only capacitor (C1 in the schematic of an improved Ir sender) can be substitutedfor any near value cap that is rated for at least 10.0 Volts DC. Though this cap canbe substituted, changing this cap's value will change both the frequency and dutycycle of the pulsed Ir output.NOTE: You must remember to observe polarity, the direction the cap gets placed

http://www.greatplainselectronics.com/search.asphttp://www.greatplainselectronics.com/search.asphttp://www.greatplainselectronics.com/default.asp


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into the circuit, if you use electrolytic or tantalum capacitors.

Ir LED (Sender)Industry PN: QED123Radio Shack PN: 276-143 or 276-143CWMS PN: A-14231WMS PN: A-16908 (assembly with bracket)“Side looking” photodiode for getting into smaller spaces like the small slot inbetween opto-interrupters; as used on drop targets and flipper optos.

Ir Transistor (Receiver)Industry PN: QSD124Radio Shack PN: 276-145 or 276-145AWMS PN: A-14232WMS PN: A-16909 (assembly with bracket)“Side looking” NPN phototransistor for getting into smaller spaces like the small slotin between opto-interrupters; as used on drop targets and flipper optos.

Resistor Substitutions Any of the resistors may be 10 or even 20% tolerance. Any of the resistors may berated for 1/4 or 1/2 Watt. NOTE: It is best to keep R1/R2 (330 Ohm) and R3 (330Ohm) 1/2 Watt resistors. But, as these testers will normally be pulsed for a shortduration, 1/4 Watt resistors will work for this application.

PARTS SOURCES

Pinball Parts Suppliers - USGreat Plains ElectronicsPinball Life

Pinball Parts Suppliers - OUSPinball Heaven

Electronic Parts Suppliers - International

Electronic GoldmineRadio Shack

http://www.radioshack.com/http://www.goldmine-elec.com/default.htmhttp://www.pinballheaven.co.uk/http://www.pinballlife.com/http://www.greatplainselectronics.com/default.asp


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SCHEMATICS


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Schematic of an Ir receiver

Schematic of an improved Ir receiver


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Schematic of an Ir sender


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Schematic of an improved Ir sender

OPERATION

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The Ir Receiver The visible LED will glow dimly in ambient room light. And, it will light more brightlywhen it detects an Ir beam. The receiver is sensitive enough and has a quickenough response time to pulse with modulated Ir signals; such as the signal from theImproved Ir sender or remote controls for television sets.

The Improved Ir Receiver Like the more basic Ir receiver, the visible LED on this improved receiver will glowdimly in ambient room light. And, it will light more brightly when it detects an Ir beam.But due to the additional stage on this receiver, it is even more sensitive to Ir light.

So, it can more easily detect Ir light from a greater distance than its more basiccounter part. Either receiver should be useful as a troubleshooting tool for testing Ir LEDs used in pinball machines. This receiver is also sensitive enough and quickenough to see the pulses of modulated Ir signals.

The Ir SenderThe Ir sender simply sends a constant and narrow beam of Ir light with a wavelengthof about 880nm.

The Improved Ir Sender The Improved version of the Ir sender gives a modulated square wave pulse of about 3.0Hz with a 25% duty cycle. This flashing pulse is unlike any signal or diagnostic LED pulse used in any pinball machine.

NOTE All pictures in this article are courtesy of Lloyd at SS Billiards .

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