$~ ,~6 R ~ D BO X W)~C ~\ .1 \~0 ~ C ONSTRUCTION The largest units in the .ed box are the telephone earpiece and battery. Since the unit works on ~V and has no coils, lOV parts can be used. The }¯sh b~ttons are high qual~ty units tbat won't bonnce on you and fire the bo~c twice. Grayhil1 makes some good ones. Snap action are the best, but they make nolse when you hold the box up to the phone. Different earpieces or speaXers will produce different volumes. If a low im- pedance (8-320hrns) speaker is used, less volume and more battery drain will result. Increase the velue of the 10 mid. output capacitor with low 1mpedance speakers, and increcse 22K gain resistor if necessary. Remember, with a red box you are going to play [t for an operator who vrill easily recognise a faul~ tone pulse. So make your solder connectlons ffght & use good svritches. Cover the spaaker holes wlth a small patch of ~in fo~m to prevent gook from ~y~ng into the magnet. OPERATING PRINCIPLES The red box consists of four sections, the oscillator, the f~p~]lop, ~e timer and the amplifier. To understand how these prodoce the necessary tones we'H take for example a dime sound. A dime is two pulses of2200 cycles, eech being 60 m;lleseconds long, wifh a 60 ms. space between then. When you press the 10½ botton, the Oip-i~p starts turning on and off, on for 60 ms. and off for 60 ms., continnausly. This in turn shor~ out the oscillator, producing on and o~ pulses to be fed to the amplifier and speaker. How do we get only 2 beeps7 Well, when you press the button, the t~mer starts. After 180 ms. it turns ofE the ~ip~flop, thus stopping the tones. Other sonnds are produced by changing the speed of the Di~flop and the delay of the timer. Also, the two RC pairs of 1M and . 047 pulse the timer and the shorting transistor, to start the timer and flip~Ilop at the same time . Current drain is approx. 7 ma, so don't worry about t~e battery. You wil1 hear some leakage after the tone sounds if you keep holding the button down, but this is alright if it's ~int or if you let go. TUNING First, ad~ust the 30K osc~ll~tor trimmer to produce a beep wLen a button is ~shed. Ihen, simply call a friend at a pay phone and ha~re him deposit money. I~ne the oscillator to the same pitch as the beeps you hear. If the oscill~tor is too high, raise the . 0033 cap to . 0047. If ~e range of t}ie trimmer is too small, add a 30K series resistor. Now, you should get one, two, and 5 beep~ for 5,10, and 25, If not, youtll need to adjust a bit. If you get only 4 beeps for 25, raise the 620K resistor. This may, however, change $he 5 and 10 beeps. l:he 680K resistor is the number of beeps for the dime, and the 120K is for the 5 button. The 150K resistor controls the speed of the ~lip-Eop for 25. If you get 5 beeps, but they're too slow compared to the phone your friend is at, you can speed them up by lowering it. This will give you more beeps, however, in the sarne period of time that used to give you 5 beeps. So then you should lower the 620K untI1 you get 5 beeps aguin, and then check for proper beeps on the other buttons. Al~.~ays adjust 25 œirst, ~en do 5 and 10 5; = 60 on 10~ 60 on, 60 o~, 60 on 25~ 35 on, 35 off(5 times) C ALLING Go to a psy phone, dial your number direct(after depositing a dime)(or 20½} and when the operator comes on she'll ask for more money, and possibly even return your dime. Now, very slowly and quietly put the red box up to the mouth- piece and press one button per coin, ~nd be sure to pause several seconds in between each ccin, just as if you were reaching for the money in your pocket and fumbling to put in the coins. If the operator gets suspicious lt could be for two reasons; first, you may be off tune or off sp~d. In that case tune lt. Sec- ond, the operator may be suspicious because in some areas a vlsual indicat- ion of insertion of coins is provided for the operator., So the ~perator rnay say something like ''I'm sorrv, str; but tbat didn't registern. Just mosey along to ar~other phone ~oth. Youell find the red bo~ is ~e safest box to use and easy and fun to use, too. Even the operator will thank you' ~ ~,~ H _~ ~ O G? ú~ m.N g: ~ r~s $ ~ ~ a) c) 0 ~ .. N ;8 ~. ~ 3 ~ a ~ ~ ~ ~ ~ ~ b ~, ~ ~ ~ ~ , s ~ 3, 1 ~ j ~ ~ ~ ~ ~ ~ %2 o ~.~5!411l,1~ IMPORTANT NOTICE . . about the enciosed 1973 telephone credit card. To make certain no unauthorized person ;s using your card. the tele- phone operators who handle credit card calls may ask you a question or two whenever you place such a call They're the type ol question that can be answered easi~y and quickly by a person having a credit card, but shouid discourage an unauthorized user Irom trying to complete the calt. We hope you~ll understand tbat our operators will be doing lhis for your protection and ours As an added precaution we urge you to treat this card as you do your other credit cards. ú Notify your Business Off;ce representative at once if it is lost or stolen. ú Do not give the card or number to anyone else to use Thank you for your ccoperalion. (3) New Yo~l~lephone Since credit card owners are receiving these notices witb their new credit cards we can expect to play some games with the operators this year. Doolt sweat, the questions are only designed to scare you and make you han; up, thus giving it away. hongh you might get a few questions like the name of the company, cit,r or area code of the credit card number, you'l} ha~re no problem if you keep cool. Ihe operator knows at most the name of the city and area code ~ not the company's name. So have your number memori~ed, and if you need the code numbers for certain cities, get YIPL #8, and be sure to read our reprint on.making credit card calls. Also write in and tell us what kind of questions operators are asl„r~g in your nart of the countrv. 1 2 ~g