C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

[Merlin]

One for the reverse engineering specialists here, i.e. Zetr0, rkauer, etc..

This was posted on Lemon 64 by Arkanoid, with questions as to who may have built it.
[attachment=2:3plcn4pr]47518353.jpg[/attachment:3plcn4pr]
[attachment=1:3plcn4pr]70500568.jpg[/attachment:3plcn4pr]
[attachment=0:3plcn4pr]11061562.jpg[/attachment:3plcn4pr]

Apart from a fine piece of 80s hackery, I was wondering about the design of this beastie. From what I can make out, the unit includes a mains neon indicator, two LEDs, a resistor or two, a fuse holder, a few capacitors (hard to tell what rating and if electrolytic or not), a couple of switches, two 5v power supplies (you can see the transformers through the holes in the internal boxes) and a chip, which I believe to be an SN7416N Hex inverter / driver IC.

Now, apart from the obvious crossover of the read/write lines from one datasette to the other, I was wondering about the data LEDs and the SN7416N; it is possible that the person that designed this is using the SN7416N to clean up and buffer the signal between the two cassette drives, along with maybe driving the data LEDs?

The reason I am wondering if you guys could help me work out how this unit works is because I can maybe add some of the features of this into the updated C64S adapter I am designing; the unit I am drawing up will use an external power supply, to save power being drawn from the MIDI / Joystick port (which new PCs won't have as standard) and also to possibly provide a standalone duplication facility like this unit.

If you have any ideas about this, I'd like to hear them.

Thanks

 

[Merlin]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

Righty-Ho,

After much deliberation and study of this device along with a couple of other PC to C64 datasette interfaces, I finally think I am getting somewhere. I am designing the unit to be able to take a cheap external unregulated transformer to provide the power, which I am stabilising with a 78L05 regulator. Using the power socket option also allows for a couple of options for this design as follows.

1. A joystick port to power jack adapter can be used if you need to use the PC to provide the 5v supply.

2. Using an external power supply allows this unit to be used as a standalone datasette duplicator, if I have designed this correctly.

I am using a SN7416N inverter to clean the signal up from the read device and feed a cleaner signal to the write device, with little or no loss in signal quality. I have also allowed for the option to use spare gates on the SN7416N to drive optional 'Data' LEDs, to indicate that data is being transferred and to indicate when file transfer from the 'read' device is complete, as the LED will go out if no data is being transferred (I think!)

This unit is based on the X1541 cable design as well as Markus Brenner's C64S interface. This unit should allow TAP files to be written back to a new tape via a PC and also allow for tape-to-tape duplication for backing up tapes. It should still allow for connecting a 1541 drive to the board, for transferring disk files.

@ TC / Zetr0 etc.

Can somebody please check that I haven't cocked anything up with this design, or maybe missing something out from the schematic?

[attachment=0:3r5z0z66]Upgraded C64S version 1 - draft.gif[/attachment:3r5z0z66]

Thanks

 

[Zetr0]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

Looks good m8,

I cannot see it blowing up

the only thing concerning me is the 7416N directly driving LED's for Read / Write and READ / Write Data, but to be fair, if you got a good solid +5VDC you wont have any problems.

 

[rkauer]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

Since just two leds are used, use a transistor for each one, TTL ports can't handle that much current (15~25mA) :roll:

OK, no joking: using mini-leds you are OK (12~15mA). Just calculate the current to be 10mA or a bit less.

 

[TheCorfiot]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

@Merlin

Looks good, I think you need to add some resistors inline with the anode drives for the LED's to limit the current draw..

Breadboard prototype time

TC

 

[Merlin]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

Thanks guys, I haven't designed anything like this in a LONG time..... :thanks:

I'll add a couple of 10k resistors to the LED + lines and use mini LEDs as Rogerio suggests; I have enough of them knocking around here.

OK, the next step will be a stripboard prototype without the 6 pin DIN, to test the standalone capability and TAP writing ability of the design. If I've got it right, the unit should light the 'write' LED while the PC writes the TAP file to the datasette, to confirm that data is being written.

Just don't expect a neat prototype..... :woot:

Edit: Schematic updated to show alternative power adapter and added 10k resistors to LED + lines.
[attachment=0:168ajg29]Upgraded C64S version 1.1 - draft.gif[/attachment:168ajg29]

 

[Zetr0]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

@Merlicious

Hiyas m8y,

after reading the posties from rkauer and TC, I hit the spec for the 7416N, it wont provide enough juice really m8,

what you need is a transistor collector connected to the 7416N #3 READ out , put the +5 in on the transistor base then have the a 10k from the emitter of the transistor to the Anode (LED )

heres a schematic to help.. it uses an NPN 2N3019 Transistor... very common and less than pennies.

please check the schematic m8... I have had a fair few beers m8, being BBQ weather here *hic* so a double or best tripple check emmiter and base LOL!



good luck m8y

 

[rkauer]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

@Zetr0: masta flux, you made a mistake! :wooha:

Collector of the transistor must be hooked to +5V, use the base connected to the signal gate via a small resistor (1.5k up to 47k) or the transistor will load the gate.

 

[Zetr0]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

yep... i knew must of done.... LOL

(Base signal and Collective Power)

thats 6 bottles of Newcastle Brown (aka Bottle of Dog) and 6 576cl cans of Stella (necter of the gods)

Sorry Merly, and great catch RKauer....

okie.... back to the sauce methinks.... I just LOVE BBQ's

 

[RedDaemonFox]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

Maybe you should come back when you're sober travelocity

 

[Zetr0]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

okay....

attached some relevent pictures

again, please for the love of god, check the schematics, my spell checker is actually smoking from over use right now, and the keys are some what heavy pressing.

but yes... see attached...

 

[Zetr0]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

Maybe you should come back when you're sober travelocity

you have a thing for Gnomes dont you.... one might even be concered as such.... if i wasn't so er... half cut

Travelocisty indeed!!!

PMSL!!!

 

[Merlin]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

Take 3......

[attachment=0:2cdgqc38]Upgraded C64S version 1.1 - draft.gif[/attachment:2cdgqc38]

Does this look something like it now?

 

[rkauer]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

Looks OK now.

 

[Zetr0]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

Its looking great Merlicious, I cannot wait to see the the proto

 

[RedDaemonFox]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

just test it on a machine you can afford to fry

 

[Merlin]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

Its looking great Merlicious, I cannot wait to see the the proto

That is praise indeed, coming from you.....

Thanks

 

[RedDaemonFox]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

I see you are on vcforum too, you guys are everywhere

 

[Zetr0]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

@Merlicious

I just love a well thought out schematic my friend , and cleary shows you have put a lot of thought into it.

I see you are on vcforum too, you guys are everywhere

The internet..... is no longer a safe place.....

 

[RedDaemonFox]

Re: C64 tape duplicator - vintage hackery for Zetr0, rkauer, etc

it hasn't been since win95