Using tape relay as sound channel

reminisce about bbc micro & electron games like chuckie egg, repton, elite & exileRelated forum: adventures


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0xC0DE
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Using tape relay as sound channel

Post by 0xC0DE » Sat Aug 17, 2019 6:46 am

I thought I had seen and heard it all but yesterday I accidentally played Aabatron on the Electron.
Not a very remarkable game but the title screen music used the tape relay click as a sort of drum/rhythm sound channel.
Any other games or demos that have done that?
Also, I'm wondering if this is bad for the relay or are they built sturdily enough?
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cmorley
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Re: Using tape relay as sound channel

Post by cmorley » Sat Aug 17, 2019 7:48 am

Yes this is bad for the relay in the long term. They only have a finite number of cycles.

Many a school kid wrote:

Code: Select all

10*MOTOR1
20*MOTOR0
30GOTO10
Leave that running for a while and it will stop clicking at all!

I'm sure for a bit of percussion though it won't reduce the life a great deal (unless it is an ex-school machine :lol: )

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1024MAK
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Re: Using tape relay as sound channel

Post by 1024MAK » Sat Aug 17, 2019 8:02 am

Relay life is determined by three things, how long before the ‘back’ EMF from the relay coil kills the protection diode and then the driver transistor, how long the contacts last when switching a current, and how long the armature of the relay lasts (the moving bit that actually operates the contacts).

If well designed and specified correctly, the diode and transistor should last for the lifetime of the equipment, but it’s unlikely that the designer would have considered the relay constantly changing state....

The current through the contacts is not relevant here, because there shouldn’t be any current (unless you leave a cassette recorder connected and running).

The armature is fairly robust, but every operation it will wear a little on the pivot points and on the return spring. So if used as intended, it’s designed to last for many years. But not if it’s constantly changing state....

You pays your money and takes your choice.... :lol:

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Re: Using tape relay as sound channel

Post by Elminster » Sat Aug 17, 2019 8:23 am

0xC0DE wrote:
Sat Aug 17, 2019 6:46 am
I thought I had seen and heard it all but yesterday I accidentally played Aabatron on the Electron.
Not a very remarkable game but the title screen music used the tape relay click as a sort of drum/rhythm sound channel.
Any other games or demos that have done that?
Also, I'm wondering if this is bad for the relay or are they built sturdily enough?
Similar idea to when they play music with the click from hard disks and floppies. Some of those are very good.

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AndyF
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Re: Using tape relay as sound channel

Post by AndyF » Sat Aug 17, 2019 10:22 am

I was always worried that a MOTOR on/off without any delay at all would cause it to either overheat thorough movement or possibly (unlikely unless something was connected to the output) arc and eventually jam 'on'

I do recall having one 'B' around the mid 90's (ad-mag purchase if I recall correctly, when they were like £20 a go!) where the previous owner or one of them had thoughtfully/unthoughtfully (depends on your viewpoint) put a small wire link on the output terminals but on the underside of the board itself at the relay rather than at the socket. Same effect. Relay was still actually operational as in it clicked but I never looked to see if it was actually faulty or not as 'it worked'
Last edited by AndyF on Sat Aug 17, 2019 10:22 am, edited 1 time in total.
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Re: Using tape relay as sound channel

Post by Dave_E » Sat Aug 17, 2019 2:18 pm

One Last Game does the same thing. Written by the same person...! Different piece of music though. :-)

I never heard that effect in any other Electron game though.

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Re: Using tape relay as sound channel

Post by ZXareL&Rtome » Sat Sep 21, 2019 8:31 am

The floppotron is an old hardware orchestra.
Using old drives and scanning equipment to make music.

Worth watching!
https://youtu.be/Oym7B7YidKs

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Re: Using tape relay as sound channel

Post by 0xC0DE » Sat Sep 21, 2019 8:56 am

ZXareL&Rtome wrote:
Sat Sep 21, 2019 8:31 am
The floppotron is an old hardware orchestra.
Using old drives and scanning equipment to make music.

Worth watching!
https://youtu.be/Oym7B7YidKs
INSANE!!! =D>
0xC0DE
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maniacminer
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Re: Using tape relay as sound channel

Post by maniacminer » Thu Oct 10, 2019 12:57 am

I used to mess around with the cassette relay by writing to the Serial ULA memory address &FE10. Setting this address to zero (clearing bit 7) will turn the motor off and setting it to 128 (setting bit 7) will turn it on. Over 35 years ago :shock: , I had a laugh modifying some code that redirected the OSRDCH to a little bit o'code that played a note depending on the key being pressed, I changed it to drive the cassette relay instead. I vaguely remember the sound being somewhere between a dog growling and a LADA with broken valve springs \:D/ I don't recall any of the relays dying because of that torture. I think, in a tight enough loop, the relay doesn't have enough time to react, say;

10 DIM code% 100
20 FOR PASS=0 TO 3 STEP 3
30 P%=code%
40 [ LDA#0
50 STA&FE10
60 LDA&80
70 STA&FE10
80 JMPcode%
70 ]
80 NEXT
90 CALLcode%

I guess the 6502 will go to cycle stretch mode and be only 1MHz, so the use of timer interrupts with the User VIA would be quite predictable, as we need tone as well as duration. At 1MHz, there might be scope for volume too?

LOL I have a Beeb that needs a soak test, I might leave it on for a week running this. If the relay dies, that's not too bad. If the flyback diode D9 (near pin 2 of the 6845) dies, then Q3 (above the diode) will get zapped and may die in either a conducting state or an insulating state. I suspect the serial ULA would be safe, though.

Anyway, if components die, they were sacrificed for the advancement of science :D

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maniacminer
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Re: Using tape relay as sound channel

Post by maniacminer » Thu Oct 10, 2019 1:04 am

AndyF wrote:
Sat Aug 17, 2019 10:22 am
I was always worried that a MOTOR on/off without any delay at all would cause it to either overheat thorough movement or possibly (unlikely unless something was connected to the output) arc and eventually jam 'on'

I do recall having one 'B' around the mid 90's (ad-mag purchase if I recall correctly, when they were like £20 a go!) where the previous owner or one of them had thoughtfully/unthoughtfully (depends on your viewpoint) put a small wire link on the output terminals but on the underside of the board itself at the relay rather than at the socket. Same effect. Relay was still actually operational as in it clicked but I never looked to see if it was actually faulty or not as 'it worked'
I've seen that mod, usually because the relay was used by someone to control something else and the contacts got fried. I remember a teacher at school being happy that he could turn a light bulb on and off without needing any complicated control circuitry or low level address calls. When I saw what he was doing, I was in total awe, a 60W light bulb, soldered into 240V AC mains in a DIN connector soldered with no heat shrink over the live terminals. I do know his Beeb had a "problem" over Xmas 1983 and I never saw that teacher with his Beeb again... #-o

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Re: Using tape relay as sound channel

Post by sgb27 » Fri Oct 11, 2019 5:56 pm

0xC0DE wrote:
Sat Sep 21, 2019 8:56 am
ZXareL&Rtome wrote:
Sat Sep 21, 2019 8:31 am
The floppotron is an old hardware orchestra.
Using old drives and scanning equipment to make music.

Worth watching!
https://youtu.be/Oym7B7YidKs
INSANE!!! =D>
I want to make this one day:
https://www.youtube.com/watch?v=93T0mVddBgM
https://www.youtube.com/watch?v=Ee5evlN8Bbs

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