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G8MNY > TECH 23.08.21 08:12l 269 Lines 11781 Bytes #999 (0) @ WW
BID : 44786_GB7CIP
Read: GUEST
Subj: Autocaller with old Maplin kit
Path: IZ3LSV<I3XTY<I0OJJ<GB7CIP
Sent: 210823/0711Z @:GB7CIP.#32.GBR.EURO #:44786 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated Mar 17)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
I had built a few of these Digital Record & Playback Modules kits from 1989 for
Contest calling, ATV repeater announcements & Commercial Radio use. So when saw
a new unbuilt kit at a junk sale I snapped it up. This new build came 2nd in a
construction contest.
Although with my IC735 HF rig there is a rear Aux socket with +13.8V, that has
all of the wanted signals, I use that for Demo station AF PA connection, so I
did not want use it here. I managed to used just the mic plug connection, the
max rating of the 8V @ 1A peak, incuding the radio! I found I had some
sensitive DIL package 12V 1K coil DIL reed changeover relays worked OK on 8V!
(but not all of them!)
LS
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ /Repeat\ rep /Mess\ ³ ³ IC735 ³
³(Play) ³ Delay ³LED³ Time ³³ ³ ³
³ \On Off/ \ / ³ ³ ³
³ ÃÄÄ´MIC ³
³(Mem ) run level ÃÄÄ´PTT ³
³ LED ____ LED ÃÄÄ´LS ³
³ /MIC \ ÃÄÄ´+8V ³
³(Rec ) ³Socket³ (H/P) ÃÄÄ´0V ³
³ \____/ ³ ³ ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
Controls & Connection layout
THE KIT
It consists of an Electret Mic, 2 dual op-amps LF442 IC1 & 2, a dedicated A-D-A
sound 40pin IC3 UM5100, logic IC4 74HC133, 256K memory Ram 62256 IC5, & 5V reg.
IC3 has clock output that is used to make -ve rail for the opamps. For fixed
work, the ram can be an eprom, a seperate add on kit is an eprom programmer
(plugs into SK1) & banks of eproms can be use together for multi messaging etc.
P1 P2 P7 P8 P10 P12 P11 Mem Links
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ P1 Electret Mic
³' ' ' ' ' ' '| | | ÚÄ¿³ P3 AF Output
³ LED ÚÄÄÄÄÄ¿| | | ³ ³³ P10 Play
³RV1 TR1 TR2³ IC4 ³ÚÄÄÄÄ¿³ ³³ P11 Record
³ ÀÄÄÄÄÄÙ³ ³³S³³ P5 +8-14V in
³ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄ¿³ ³³K³³ P7 +5V out
³ÚÄ¿ ³ A-D-A ³³RAM ³³1³³ P2,4,5,6,9,12 0V
³³ ³ ³ SOUND IC3 ³³IC5 ³³ ³³ ÚÄLED
³ÀÄÙ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÙ³ ³³ ³³ Gain IC1 ___ Data TR1 ___
³ IC1 RV2 ³ ³³ ³³ MicÄÁÄ´>Ä´>Ä´A>DÃÄÄÄÄÄÄÄÄÁÄÄÄ´RAM³
³ ÀÄÄÄÄÙ³ ³³ ³IC3³ Address ³MEM³
³ ÚÄ¿IC2 _ÚÄÂÄ¿reg ³ ³³ AFÄÄÄ<ÃÄ<ÃÄ´A<DÃÄÄÄÄÄÄÄÂÄÄÄÄ´IC5³
³ ³ ³ -³ ³O³ ³ ³³ IC2 ³ ³stop ÚÄÁÄÄ¿ ÀÄÄÄÙ
³ ÀÄÙ. . . . ~ÀÄÁÄÙ ÀÄÙ³ play--------´OscÃÄTR2Ä´gate³ ÚÄÄÄ¿
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ rec---------ÀÄÂÄÙ ÀÄÄÄÄÙ ³reg³
P3 P4 P6 P5 Speed IC4 ÀÄÄÄÙ
The op-amps are used with the A-D-A input/output to generate the data, filter &
replay it. It is fairly flat 300Hz-3kHz with up to 40dB S/N, @ 10 seconds
message time. Up to 23 sec is usable, but quality is much reduced. For external
mic/AF use, I removed the mic's DC feed R.
BELL & WHISTLES
1/ Message time.
I extended the clock frequency preset RV2 to the front panel, to enable long or
short messages, & also variable speed on recorded items like CW.
2/ Status LEDs
I also extended the level LED & added a "4 Pulse" LED from a high order count
address line A12 on the programmer socket. This gives a simple end of message
warning.
S3ÄÄÄ2k2ÄÄ´>ÃÄ¿
// 0V
With the later repeat toggle latch (7/), I also added a "Repeat On" LED too.
3/ Battery backup.
To store the message on power off a battery backup is needed to power just the
Ram to > 2.4V. Cut the 5V track feeding the Ram & add..
1N4148
+5VÄ´>ÃÄÂÄ330Ä¿
³ _³_ 3x
Ram 28ÄÄÙ _Ü_ 100mAH
_Ü_ Nicads
_Ü_
_____________³___0v
4/ Second message Ram.
I piggy backed on a 2nd message RAM. I soldered the first directly into the PCB
with the Chip Select pin 20 track cut, & added a socket on top for the 2nd RAM,
also with CS pin isolated. I use a locking push switch to select the RAM.
+5VÄÄÄÄÂÄÄÄÄÂÄÄÄÄÄÄÄÄ¿
100K 100K ³ Úßßßßß¿
RAM1 ³ ³ RAM2 ³ ßßßßßßß-20
20ÄÄÄÄ´ ÃÄÄÄÄ20 ³ =====Ãßßßßß´======
Ào oÙ ³ cut PCB to pin 20
mem1 \ mem2 ³
³ 100K
Battery Save \³_________³ By adding this NPN the power off battery
Earth e/³npn backup current is reduced from mAs to <uA!
ÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄ0v
5/ Record Rx.
This uses a non locking double pole changeover push button, to trigger record
mode with a one shot C & a change over from mic to Rx LS record, when record
button is held in.
Ham MIC>ÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄ>Rig
o Mic
AF in____________/REC
Module o ÚÄ100KÄ<Rx LS
(mic DC) ³ Rx
(removed) ÀÄÄ>Level
47K
Rec One shot o ³
ModuleÄÄÄÂÄ´ÃÄ¿__/REC ³
(pulse) ³10n ³ o ³
ÀÄ1MÄÙ ³ ³
_________________³____³________0v
6/ Mon LS.
I added an old LM386 360mW amp & 8R LS as monitor. But used an AF diode gate in
front of it to mute LS, unless it was playing or recording off the Rx LS line.
+ÚÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÂÄ<+8V
===22u 100K AF 100K ³
Á ³ Gate ³ 3³\6
Play AF>Ä´ÃÄÁÄ´>ÃÄÂÄ´<ÃÄÁÄÄ´ÃÄ´LM\ 5 +220u FB _/³
u1 ³ u1 ³386'>ÄÄÄÄÄÄÄÄÂÄÄÄ´ÃÄÄðÄ´ ³Mon
Rx 100K ÚÄÄ´ /8ÄÄ¿10u ===u1 Ú´_ ³LS
Rec >ÄÄÄÄÄÄ´<ÃÄÄÄÄ´ ³ 2³/ ³1 === ³ ³ \³
³ ³ 4³ ÀpotÙ+ 10R ³
Relay >ÄÄÄÄ´<ÃÄÄÄÄÙ ÄÁÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÁÄÄ0v
Play Pot 47K= preset Mon Vol
7/ Repeat timer.
I was going to use a 555 timer. But close investigation I saw an easy solution,
just an NPN & zener with a CR in front of it. Although this worked well, I soon
realised a toggle flip flop bistable was needed too, for ease of operation.
Repeat On off with Delay control (a switched vol control pot)
ÚÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÂo\__+8V
³ ===u1 ³
³ ÃÄÄ¿ ³
³ _³_100K ³
Repeat_³_ \_/ ³ ³ ÚÄ<Play button (earth)
ON =\ / ÃÄÄÁÄ´>ÃÄ)ÄÄÄÄÄÄÂÁÄÄÄÄÄÄÄÄÄ>Module Play (CMOS logic)
LED ÄÂÄ ³ ³ ³
³ ³ ÚÄ´>ÃÄ)ÄÄÄÄÄÄ)Ä>Mic PTT stop _
1K ³ ³ 10K ³ /|
³ ³ ³ ÃÄÄ´<ÃÄ)ÄÄÄÄÄÄÄÄÄÂÄ1M DelayÄ¿
ÃÄ100KÄ´ ÃÄ22KÄ´ ³ ³ Control ³
³ \/ ³ \³ ³ / ³ mic relay
T1 \³_____/\____³/ T2 T3 ÃÄ´>ÃÄÄÂÁÄÄÄÄÄ´>ÃÄÄÁÄ33KÄÄ<+8V on Rx
e/³ ³\e e/³ 5V' +³ 0V on play
³ Flip Flop ³ ³ ===22u
ÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ0v
On = repeat = Off Repeat Delay CR
The 33K sets the min delay to about 1 second Rx, & +1M to >60 seconds. Turning
the delay timer on (or rig power up), turns on T2 via u1. This ensures the 22u
can't charge up.
Pressing the Play button fires the module to play & also turn off T2 that flips
the toggle. T1 now on, lights the Repeat LED. T2 off lets 22u charge up when
the play has finished, from the 8V via the Mic relay coil. When > 5V, T3 is
turned on initiating another play.
Pressing the Mic PTT puts a good earth via diode to T1's base turning it off, &
flipping the toggle into not repeat mode. So does the intial power on pulse via
u1 & diode with C charging 100K R.
RIG INTERFACING
A/ PTT
This was not straight forward! The kit does not have an ON PLAY line, so I
detected the fastest run clock A0 on S15 to generate a PTT line.
mic AF>ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄo
bead 10n \ÄÄÄÄÄ>Rig mic
Module Play AF>ÄÄRFCÄÂÄÄ´ÃÄ47kÄÄÄÄo mic
³ preset relay
Headphone relay<ÄÄÙ play level
mic PTT>ÄÄÂÄÄÄÄ´<ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ ³
Kill ³ +8V ³
Run <Ä´>ÃÄÙ ____³____ ³
(TR1 Base 10k) ³mic relay³ ³
(Fed via diode) ÀÄÄÄÄÂÄÄÄÄÙ o Play ³
ÃÄÄÄÄÄÂÄÄÄo<ÄÄÄÄÄÄÁÄÄÄÄÄÄÄ>Rig PTT
WE Ram27ÄÄÄÄ´<ÃÄ¿ ³ _³_ Push held
0V record pulses³ ³ /_\ in stops Tx
³ ³/ ³
S15ÄÄÄÄ27KÄ´>ÃÄÂÁÄ10KÄ´>ÃÄ´BC182 ³
A0 Run +³ ³
clock 4u7=== ³ ³
ÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÁÄÄ0v
As I did not want the PTT or mic relay (mic powered from rig) operated on
record I used the 0V Write Enable pulses to discharge the 4u7 to defeat that
action.
B/ Headphones.
The last op-amp IC2 is just powerful enough to give playback headphone level
with cap changed & a NFB gain pot added, to the last unit gain amp. So I added
another reed relay changeover for the headphone feed.
ÚÄÄ>Mic playback gain
³
Headphone_ oÄÄÄÄÄÄÄÄÄÄÁÄÄRFCÄÄ<Playback Module AF (modified louder Op-amp cct)
Relay\o bead
ÀÄ150ÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ<Rig LS
100K
³ +8V
To Rec<ÄÄÄÄÄÄ>Rec level ____³____
Button 47K pot ³H/P relay³
³ ÀÄÄÄÄÂÄÄÄÄÙ
³ ÚÄÄÄÄ´
³ u1³ ÃÄÄÄÄÄÂÄÄÄ> LS amp mute
³ === ³/ _³_
S15ÄÄÄÄÄÄÄÄÄÄ47KÄÄ)ÄÄÄÄÄÄÄÄÄÁÄÄ´BC182 /_\
Run pulse ³ ³\e ³
ÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÁÄÄ0v
The 150R in the headphone feed is selected to give suitable level from the
rig's LS line.
WIRING UP
With all these mods the unit is quite complex, but I managed it with just 1
additional vero PCB & loads of coloured wiring, CAD documenting it as I went.
One thing I did miss was the effect of the LS magnet on the nearby reed relays,
once the lid was on! A tin can cover glued/soldered over the magnet was needed!
CALIBRATION
There are several pots in the system, a bit of a round robin to get right
straight away, some need to be set first, before the others are adjusted.
1/ Set the original mic in gain RV1, to "just distort" if shouting into the mic
(Level LED flashes brightly).
2/ Set added Playout gain level on IC2, to give adequate headphone level.
3/ Set Playout level mic feeding preset to give same Tx level as the live mic.
4/ Re check 1 2 & 3 for best results.
5/ Set Rx LS vol to typical level on a Rx signal. Set Rx Rec pot for same
flashing LED level as with mic record.
6/ Set Mon LS play level to a comfortable background check level.
ERGONOMIC CONTROLS
In use the controls make it very easy to use. With headphones on you can hear
the Rx, pre-recorded messages, Tx or not depending on keeping the play button
pressed. A stab of the record button, records the mic for the 4 LED flashes, or
keeping the button pressed, it records the Rx AF, were the rig Volume control
setting the level all heard in the headphones.
Without the headphones you just hear playouts on the LS. but not when recording
the mic. Pressing the mic PTT kills the player & the repeat toggle.
Recordings should be made with little/no AGC action & "repeat" set to OFF!
Replay of Rx recordings come over best if the rig's mic processing is "OFF"!
See my other tech bul on "PA instability in ICOM IC735" & "IC 735 No RF Output
Fault"
Why Don' U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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