All of this gave me an idea though.
If one would use a logic gate, protected via a resistor or voltage divider and a zener diode at the input.
Then, at the output use something with an open collector or an open emitter.
Will that work ?
The IC, 3 resistors, 3-4 capacitors and a zener diode are needed. The TL712CP in this circuit is a trigger with a defined hysteresis of about 80mV. Signal amplitudes below 80mV do not change the output. Signals above that voltage change the output state. Therefore noise will not produce small peaks.
After some experimentation, I have the current configuration that to me looks promising. It provides a signal that is between 900mV and 3V peak to peak.
The previous circuit looked great on oscilloscope, but the ZX did not like it. I had to change R4 and R5 to offset the negative peak to around 1 V and top peak to 3V to get the ZX to load.
UPDATE: this circuit is good enough that I actually have to lower input volume on some games in order for them to load. Might need to make a revision and find a way to balance it a bit better by its own.
UPDATE2: I should not that I am testing with onboard realtek audio from my pc, since it is a very average sound card, and the output quality is not that great, but also quite representative of what you find in pcs today.
The IC, 3 resistors, 3-4 capacitors and a zener diode are needed. The TL712CP in this circuit is a trigger with a defined hysteresis of about 80mV. Signal amplitudes below 80mV do not change the output. Signals above that voltage change the output state. Therefore noise will not produce small peaks.
Greets Ingo.
Very interesting circuit.
Thanks for the pointers Ingo !
I searched my component collection, but couldn't find the comparator.
Tomorrow at work I'll see if we have it lying around, otherwise I'll order some.
Stupid me, I also forgot the 7805 regulators and the 9 volt battery.
It's time I built myself a decent Labsupply again.
Can someone recommend me some title that is very difficult to load, so I can use it for testing purposes?
Something like deviants maybe ?
It has a mini game during loading.
I always thought that Firefly was also a difficult one.
Custom loader and I believe the loader is even overwriting itself during loading.
I never managed to crack it, so I designed myself a snapshot device in order to back it up.
Something like deviants maybe ?
It has a mini game during loading.
I always thought that Firefly was also a difficult one.
Custom loader and I believe the loader is even overwriting itself during loading.
I never managed to crack it, so I designed myself a snapshot device in order to back it up.
both of these loads without problem using my current circuit.
It seems that at least my ula needs a dc offset to properly handle the signal.
If you need an adjustable circuit I recommend replacing R4 with a 1.5K potentiometer. Or even 1K allows you to adjust the offset.
I was able to speedload Deviants at 14700 baud with a 1.5 meter long cable. With a shorter cable I guess it should be possible to load at even higher baud rate. :)
Good to read that you have it working now.
Have fun !
Thank you. I hope it will serve to help someone who is doing the same mod and cant use the LA6324 amplifier that is built into the datacorder (mine is toast).
Hmm. I have to check the data sheets on those to make sure they are pin and electrically compatible.
AFAIK They are totally compatible. Different manufacturers, same quad op-amp. Checked datasheets long time ago. Never had to replace some LA so far though.
AFAIK They are totally compatible. Different manufacturers, same quad op-amp. Checked datasheets long time ago. Never had to replace some LA so far though.
Ok. Thank you for that. Before I got this +2 it had suffered something horrible. So much circuits blown and then poorly repaired (or not at all).
Ok. Thank you for that. Before I got this +2 it had suffered something horrible. So much circuits blown and then poorly repaired (or not at all).
Which tape deck circuit model is that? I have seen at least two, perhaps three different boards. They have some minor differences at least in the wire soldering placement.
I got one which had some sort of mod. I think it was supposed to enhance the audio levels, so there was a zener in series with the blue wire, a cut track and a wire routing one of the op-amps straight to one of the inputs. I had it all undone prior to fixing it. It wouldn't save with a usable volume.
I modded some of these circuits adding pins where the wires should be soldered and encased everything with modu type plugs. This makes it easy to replace the boards for testing when another gets to me for repairs.
It says; Z70501 on the circuit board.
It has a resistor added in a place that does not conform to any photos I have sen of this PCB. But I have measured input and output on the LA6324 and what goes in just does not come out. The IC is dead.
Aye most probably. Congrats on your circuit btw, loading up Deviants in one shot at high speed is awesome. Would you like to have a try at Robocop? Trying to load it from tape gets on my nerves. Never had a problem with Firefly though.
I'll check my boards' versions when I get home this Monday.
Aye most probably. Congrats on your circuit btw, loading up Deviants in one shot at high speed is awesome. Would you like to have a try at Robocop? Trying to load it from tape gets on my nerves. Never had a problem with Firefly though.
I'll check my boards' versions when I get home this Monday.
I would love to, but unfortunately I am unable to convert the .tap file to an mp3. :(
Any suggestions?
Replaced LA6423 with LM324, and hmm. Datacorder still not work properly. And ear plug mod through LM324 is not good enough for external loading. My own circuits works better. So I removed the datacorder and put back the amplifier I have built. Will look into if it is at all possible to get the datacorder to work later.
Replaced LA6423 with LM324, and hmm. Datacorder still not work properly.
Fixed one once that had a bad capacitor. The problem now is I can hear the motor humming, and sometimes there's radio interference. The tapes load perfectly, but it's such a pain to hear radio through my TV composite input when I get the volume a bit higher.
I have a couple datacorders which won't work too though replacing almost all components on the board. Weird. Replaced the LA with ones known to be good to no avail. LM's didn't do too. Can't sort it out.
What kind of component is L106? Is it a capacitor? This is one of those I didn't replace yet.
! Standby alert !
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb!
Looking forward to summer in Somerset later in the year :)
Does it look like a resistor? A lot of "small" wire ended inductors (also known as chokes) look like resistors.
Unless the inductor carries a lot of current (like in a power supply section), it is very rare for an inductor to fail.
Mark
Yes I really think that L stands for an inductance. I just need some advice of more experienced friends as I don't like to assume and don't know how to read those colour codes. it looks a lot like a cap or a resistor. Good to know it isn't worth a shot.
Comments
http://www.ti.com/lit/ds/slcs002d/slcs002d.pdf
The third scheme in this pdf shows a safe circuit that makes square wave signal from 100 mV to >3 V of any waveform:
http://www.truppel-online.de/spc/harlequin_tape001.pdf
The IC, 3 resistors, 3-4 capacitors and a zener diode are needed. The TL712CP in this circuit is a trigger with a defined hysteresis of about 80mV. Signal amplitudes below 80mV do not change the output. Signals above that voltage change the output state. Therefore noise will not produce small peaks.
Greets Ingo.
UPDATE: this circuit is good enough that I actually have to lower input volume on some games in order for them to load. Might need to make a revision and find a way to balance it a bit better by its own.
UPDATE2: I should not that I am testing with onboard realtek audio from my pc, since it is a very average sound card, and the output quality is not that great, but also quite representative of what you find in pcs today.
Very interesting circuit.
Thanks for the pointers Ingo !
I searched my component collection, but couldn't find the comparator.
Tomorrow at work I'll see if we have it lying around, otherwise I'll order some.
Stupid me, I also forgot the 7805 regulators and the 9 volt battery.
It's time I built myself a decent Labsupply again.
you can simulate any (small) circuit you want here online: https://www.circuitlab.com/editor/
I tried a solution using transistors (any npn transistor should do the job) - so here is the result:
Output amplitude is 4V (min=0V, max=4V).
Note, I did not try that circuitry in reality.
Greets Ingo.
Something like deviants maybe ?
It has a mini game during loading.
I always thought that Firefly was also a difficult one.
Custom loader and I believe the loader is even overwriting itself during loading.
I never managed to crack it, so I designed myself a snapshot device in order to back it up.
Thank you. I will test that simulator. It seems the ULA likes 1.45 to 3V peak to peak signal. I will try your circuit to see if it works as well :)
both of these loads without problem using my current circuit.
It seems that at least my ula needs a dc offset to properly handle the signal.
If you need an adjustable circuit I recommend replacing R4 with a 1.5K potentiometer. Or even 1K allows you to adjust the offset.
Have fun !
Thank you. I hope it will serve to help someone who is doing the same mod and cant use the LA6324 amplifier that is built into the datacorder (mine is toast).
You could always replace it, looks to be the same as an LM324 which are easy to get.
Hmm. I have to check the data sheets on those to make sure they are pin and electrically compatible.
AFAIK They are totally compatible. Different manufacturers, same quad op-amp. Checked datasheets long time ago. Never had to replace some LA so far though.
Ok. Thank you for that. Before I got this +2 it had suffered something horrible. So much circuits blown and then poorly repaired (or not at all).
Which tape deck circuit model is that? I have seen at least two, perhaps three different boards. They have some minor differences at least in the wire soldering placement.
I got one which had some sort of mod. I think it was supposed to enhance the audio levels, so there was a zener in series with the blue wire, a cut track and a wire routing one of the op-amps straight to one of the inputs. I had it all undone prior to fixing it. It wouldn't save with a usable volume.
I modded some of these circuits adding pins where the wires should be soldered and encased everything with modu type plugs. This makes it easy to replace the boards for testing when another gets to me for repairs.
It has a resistor added in a place that does not conform to any photos I have sen of this PCB. But I have measured input and output on the LA6324 and what goes in just does not come out. The IC is dead.
Aye most probably. Congrats on your circuit btw, loading up Deviants in one shot at high speed is awesome. Would you like to have a try at Robocop? Trying to load it from tape gets on my nerves. Never had a problem with Firefly though.
I'll check my boards' versions when I get home this Monday.
I would love to, but unfortunately I am unable to convert the .tap file to an mp3. :(
Any suggestions?
You can find it here:
http://www.worldofspectrum.org/utilities.html
It can save TZX and TAp files to WAV.
(Note: I will get an LM324 and repair my datacorder, just to have complete system. And keep this circuit as the EAR in port).
Amazing!
Fixed one once that had a bad capacitor. The problem now is I can hear the motor humming, and sometimes there's radio interference. The tapes load perfectly, but it's such a pain to hear radio through my TV composite input when I get the volume a bit higher.
I have a couple datacorders which won't work too though replacing almost all components on the board. Weird. Replaced the LA with ones known to be good to no avail. LM's didn't do too. Can't sort it out.
What kind of component is L106? Is it a capacitor? This is one of those I didn't replace yet.
Unless the inductor carries a lot of current (like in a power supply section), it is very rare for an inductor to fail.
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! Standby alert !
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb!
Looking forward to summer in Somerset later in the year :)
Yes I really think that L stands for an inductance. I just need some advice of more experienced friends as I don't like to assume and don't know how to read those colour codes. it looks a lot like a cap or a resistor. Good to know it isn't worth a shot.
Will check something else.