sceiv

More documents

Recommendations

Info

Pin 17 is the GT (guard time) control; it is a trigger-type input. The level on pin 17 is arranged as a delayed EST via C7 and R12. If the detection of DTMF is long enough for voltage at pin 17 to build up with time, it can be considered a valid DTMF signal. The STD output line (pin 10) will nag logic high since it is connected to output data. enable (pin 15 ) . T hat w ill e na ble lin es (pin 11,12,13,14) to present a numeric value fo r the decoded DTMF data. Yet, it takes the same delay for an RC circuit to d ischarge. T hat means TALKOFF detection can still occur after a val id DTMF signal has disappeared while C7 is still charged up. That is the reason for includ ing D9 and R II. They are there to provide a fast discharge on C7 and ensure an im me d iate full de lay guarding once a valid DTMF tone is gone. Circuit Operation Thc ci rcuit is preUy straightforward. The MT8870 monitors any audio corning from the rec e iver. Thc internal speaker of the receiver is muted while th e externa l mo nitor sp e aker is switched by Q I o r a manu al co ntrol bypass switch (Q I is driven by the internal command decoding logic). The decoded BCD numeric data follows the format shown in Table 1. This data is decoded into 16 individual outputs by the hex decoder. Simply speaking, if you received a DTMF ... .. entry, you will get a logic high on pin 19 from the 14514. All these 16 ou tputs are connected to the program board, which is o nly a 16-pin DIP IC socket. UI-U3 and F I-F4 are input wires to the corn mand decod ing log ic. The command programming is completed by jumping thcse wires into the corresponding pins on the program board. For example: If you want to program you r station ID as number 13301, you just have to plug wire UI to pin 3, U2 to pin 3, and U3 to pin 10 of the program board-it's as simple as that! The command decoding logic is just a bunch of gates combined wi th RC delay ci rcuits, thanks to the extra high input impedance of CMOS. That makes it possible for electric charges to stay at their inputs for hours until absorbed by a shunting resistor. Let's take one simple section as an example. Look at the 4081 dual input gates. T he y form a simple two-digi t command decoder, Thcy are all connected to an RC circuit formed by R4 and C4. This RC will fonn a delay of about one second. That is to sa y, if there has been a logic high coming through 04, C4 will keep the charge and R4 discharges the circuit to a logic low level within one second. If another logic high is received on the second input (FI-F4 matches a se lected DTMF tone received) before the discharge is completed, the selected gate will open and a logic high will appear at the output. This output can be used to drive external ci rcuits. To change the delay du ration, just 22 73 Amatetn: Radio Today . J une,1992 • • • • • • • • • •• • • • • • • • • ,..---,. • •• • • • • • • • • • • • • •••••••• • • • • •· • • • • • • • .' • \ • • • • • • • • • • • l E:O~ -(liP _ . . • • • ••• • • • • Fig UT~ 2 (a ). PC board/ oilpanem (bottom layn). (b). Top taver: Figure 3. ParTS placement. change the RC values. The larger the resistance or capacitance, the longer the waiting delay on the second digit. One factor which affect s the accuracy of these timi ngs is humidity. This effect will be further emphasized if the resistance value is high (say, exceeding 5 megohms), A delay longer than 120 seconds is not recommended. although it can be approached (the typical value fo r a 1200second delay is 5 meg/47 jlF). r chose tanta lum capacitors because they are small er and enclosed in a better package. Also. they can stand higher changes of temperature and humidity. Now, let's look into the command decoder in more detai l. U I , U2. and U3 are programmed as the station ID number. The 4017 is a decade counter equipped with auto-reset ability (via 05, RS, C5, and inverter E). The • • • • • • • • • • .. .. .... .... .......... D • • • .............. •••• • • • • DO pin is the output o f decade stage 0, and it will stay logic high as lo ng as the counter stays idle . C5 is charged up continuo usly until the fi rst OTMF entry is detected. That causes the coumcr to step up by one, and DO will go to a logic low status while D1 goes to a logi c high state. Once that happens, the charge at the input of inverter E will be discharged by R5 and approach logic low within three seconds. In this three-second period the counter can still count DTMF activities and move the logic high status from 0 1 to D2 if a second DTMF tone is detected. Once the three seconds have passed. the 4017 will be reset and all command entry has to stan from first digit again. If the first d igit of the DTMF en try is correct (matches Ul ), two inputs of the 4073 will be on logic high (s upplied by 4017 0 1 • •• •
~ASTRCN 16,;, CORPORATION 9 Autry Irvine, CA 92718 (71 4J 458-7277 ASTRON POWER SUPPLIES • HEAVY DUTY. HIGH QUALITY. RUGGED· RELIABLE. Sl SE RS-l SERIES RM SERIES RS-A SERIES RS-M SERIES MODEL VS-SOM MOOEL RS-35M MOOEl RM-35M MODEL RS-7A VS-M AND VRM -M SERIES SPECIAL FEATURES 'ERFORMUCE SPECIFICATIONS .. SOUDSTATE ELECT!O'ICAllY REGUlATED .. INPUT VOLTAGE: 105-1 25 VAl; .. FOlD-BACK ClJ RRENT UN ITING PrOIeClS Power Supply .. OUTPUT VOlTAGe: 13.8 we :!: 0.05 volts from excessive ClJJl'ent & continuous shorted outPUt (lmernally Adjustable: 11-15 VDC) .. CROWBAA OVER VOUAGC PROTECTION on all Models .. RI PPlE Less than 5rrN peak to peak (lull load & ._ctJl R~ IS-4.\, 1s-5A. IS..4L IlS-5I.. low Illlt) .. MAINTAIN REGlIl.ATlON & LOW RIPPLE at low li ne input .. All units available in 220 Vw.; input voltage Voltage (except lor SL-llA) .. I£AVY DUTY HEAT SINK .. QlASSIS MOUNT RISE .. THREECONDUCTOR POWER CORD except 1MRS·JA .. ONE YEARWAAAAHTY .. MADE INU.S.A. Colol1 Coniinuool ies- Sill liN] Shipping MaDEL Gray 81adl: Duly lAmps! (Ampsl " ~W "l1 Wlllbs.1 .. l OW PROF ILE POWER SU PPLY SL·llA • • 7 11 2V. x 7'11 x !f'lo 11 Conlinul)lI$ I&S' Size (IN~ S hl ' ~"j MOllEL Duly [Amps) IA mlll) H"W " Wll lll. .. POWER SUPPLIES WITH BUILT IN CIGARETTE LIGHTER RECEPTACLE RS-4L 3 4 3'h X6'/. x 7't. 6 RS-5L 4 5 3'h X6Y. x 7 ' t. 7 • 19" RACK MOUNT POWER SU PPLIES CDnlinulU, ICS· Sin II NI S hl '~ " , MODEl Uul, [Amp. 1 IAlip11 Hx Wx 0 WL "- RM -12A 9 12 5't. x 19 x 8'4 16 RM-35A 25 35 5'10 x 19 x 12'h 38 RM -50A 37 50 5'1ox19x12'h 50 RM-611A 50 55 7x 19x 12'fl 60 • Separate Volt and Amp ueters RM -12M 9 12 5't. x 19 x S't. 16 RM-35M 25 35 5'/0 x 19 x 12 '1'1 38 RM-50M 37 50 5't. x 19 x 12Yt 50 AM -60M 50 55 7x19x12'h 60 """ CUli""1 ICS' Sin III) Ol"i', MODEL 6n, ,." lit, (A_' ll IA_, I) I xW xD WI. llh.1 RS-3A • 2.5 3 3 x 4'10 x 5'4 4 RS-4A • • 3 4 3"'4 x 6'11 x 9 5 RS-5A • 4 5 3'" x 6'11 x 7'4 7 RS-7A • • 5 7 3"'4 X 6'" x 9 9 RS-lB • • 5 7 4 x 7'It x 1034 10 AS- lOA • • 7.5 10 4 x 7'It x 1034 11 RS-12A • • 9 12 ew xexs 13 AS-128 • 9 12 4 x 7'1> x 10'4 13 RS-20A • • 16 20 ex s x rcv 18 RS-35A • • 25 35 5 x 11x 11 27 RS-50A • 37 50 6x1334x11 .. C••II..... ICS' Sin [II) UI"I" MO DEL 111, IA_,I) (A_' ll I xW x l WI. (Ih .) • ~e volt and Amp meter RS-1 2M 9 12 4.... x a x a 13 • Separate volt and Amp meler5 RS-208l 16 20 5 x 9 x10'k 18 RS-35M 25 35 5 xl1 x 11 27 RS-SOM 37 50 6 x 13'" x 11 .. • 5epMa1e Volt and Amp Meters . Output 'WIlage adjusta ble from 2·15 voIIS . Cwrent limit ad;Jstabie from 1.5 amps to Full Load "Iii,.... lOS· Sin lUll S~I" II' MODEl II', (A_'ll Ib,s) I x Wx l Wl·llh.) @13.8VDC @l OVOC @5VDC @13.8V 'lS-12M 9 S 2 12 4';, x 8 x 9 13 VS-2OM 16 9 4 20 s x s x tow 20 VS-35M 25 15 7 35 5x 11x11 29 VS-SOM 37 22 10 50 6 x 13'" x 11 .. RS-S SER IES • variable rack mount POW!If supplies VRM-35M 25 15 7 35 5V. x 19 x 12'h as MODEL VS·35M VRM-50M 37 22 10 50 5V. x 19 x 1217 50 • Built in speaker """ C" U..... ICS' SlnlIN) S.I"I•• MODEL Gn, ''''' I II, lA- ' ll A_,s I xW xD WI. llh.) RS-lS • • 5 7 4 x 7'11 x 10'" 10 RS-'OS • • 7.5 10 4 x 7'1.1 x 10'" 12 RS-.2S • • 9 12 4,,", x8 x9 13 RS-20S • • 16 20 5 x 9 x 10,,", 18 ' ICS-Intermitlenl ConYnl.lliCation seeee (SO'II Duty Cycle Smln. Dl'I 5 min. off) CIRClE 16 ON R£ADVl SEIMCt: ColAO
Page 1 and 2: JUNE 1992 ISSUE #381 USA $2.95 CAN
Page 3 and 4: ONG LE~ Greatly I Is" AMlSSB Signal
Page 5 and 6: THETEAM PUBLISHERIEDITOR Wayne Gree
Page 7: their PC to discover the "ell' visu
Page 10 and 11: LETTERS Dave KD8VI, Lakewood OH I j
Page 12 and 13: Number 4 onyourFeedbeclI CIII'd 8,0
Page 14 and 15: inary address is input to the devic
Page 16 and 17: make it easier to remove, you can m
Page 18 and 19: !'Unbet' 5 on yovr FeedbKk card VE3
Page 20 and 21: Figure 2. The wire beam for /5 and
Page 22 and 23: Number . on r- F..ll'Mc~ ~ Touch-To
Page 26 and 27: output and charged up C I). If the
Page 28 and 29: Number 7 on your Feedback e.rd Buil
Page 30 and 31: •• ,. ,.,..,. " " .. :.~'" ,.-
Page 32 and 33: help reduce the " thump" problem. F
Page 34 and 35: You may elect to tinker with the in
Page 36 and 37: VE3CYC's Wire Beam Colltitlued/rom
Page 38 and 39: G S.',"m,,, ,.. ,""", , " Ol 'us,
Page 40 and 41: . ICOM'" R7000 SWEEl'lNG : 1300 CHA
Page 42 and 43: 73 Review by Bill Brown WB8ELK Numb
Page 44 and 45: 73 Review by Mike Baker WSCM The He
Page 46 and 47: planned to use. This top shelf is n
Page 48 and 49: HAMSATS Number 10 on your Feedback
Page 50 and 51: y Bill Clarke WA4BLC ELNEC Version
Page 52 and 53: _ «r • .,. .. "" lIea. .....- I"
Page 54 and 55: SANELLI TECHNOLOGY Sanelli Technolo
Page 56 and 57: Arv Number 13 on your Feedback card
Page 58 and 59: .. . - ' .,. "" . ', , -------,-"-
Page 60 and 61: SPECIAL EVENT;,m..",,"",,,..db,,k,,
Page 62 and 63: VE eeeme. Vendors need to reserve s
Page 64 and 65: QRP Number 16 on your Feedback card
Page 66 and 67: ABOVE & BE"YOND~F-- k ~" C. L Hough
Page 68 and 69: 73 INTERNATIONAL Numbet 19 011 y(U'
Page 70 and 71: TALK WITH THE KNOWLEDGEABLE PEOPLE
Page 72 and 73: ASKKABOOM MichaelJ. Geier KBfUM do
Page 74 and 75:
Natural Voice Playback Board Datavu
Page 76 and 77:
Joe Moel/, PE., KOOV PO. Box 2508 F
Page 78 and 79:
NEVER SAY DIE Continu8(/ from page
Page 80 and 81:
RTTY LOOP Marc I. Leavey, M.D., WAJ
Page 82 and 83:
Carole Perry WB2MGP Madia Mentors.
Page 84 and 85:
BARTER Tum your old ham and compeer
Page 86 and 87:
PROPAGATiiiN'''....''''~ FCC Enforc
Page 88 and 89:
WNlOI Ellel'Yday Electronics Dl tl
Page 90 and 91:
YAESU FT-1000 FT-912R FT·747GX FT
Page 92:
• 100 Watts on all nine Amateur b
show all

sceiv

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?