The Robot is a low fidelity 8 bit pitch transposer with absolutely no feelings what-so-ever. It is completely synthetic and transforms any input into a spuree of resynthesized robot jargon.
Originals need a dedicated power supply as the HT8950 chip runs off 2.4-4 volts and the power section of the original will not play nice daisy chained with other pedals. To make it a little more user friendly, I've altered the power supply to use a 3.3v regulator (LM1117V33C or similar, though watch the pinout). Here's my modified schematic:
Note: I've also included 4 extra pads on the PCB layout in case anyone wanted to do the mod lvlark describes here.
Interesting....it sounds as made for a wah pedal housing with the pedal-pot wired to the control setting. I especially liked the fx / sounds produced, while turning the control-knob. Another one on my list. Awesome work!
ReplyDeleteWow, this is very nice pedal
ReplyDeleteI wish i could build one right now, but i don't have any 8950 sadly
How about bearfoot candy apple fuzz gold from tagboard for the next fuzz friday? I can verify their fixed layout ;)
Looks interesting. Can you find an actual schematic? Trying to decipher stripboard is not my favorite. haha
DeleteSure, I'll look for it and post here
DeleteThis one should work https://guitar-gear.ru/forum/index.php?app=core&module=attach§ion=attach&attach_rel_module=post&attach_id=40804
DeletePotentiometer "A" its mean linear or logarithmic?
ReplyDeleteA-Logarithmic
DeleteB-Linear
C-Anti-logarithmic
4p3t seems wrong to me, why not a 3P4T switch instead? Many layouts around seem not to work... updates?
ReplyDeletehey! awesome proyect.. is it verified? i've seen some builds with a pot instead of the trimpot for gain... i can't decide whether to do that or not as I don't know if it's really worth it... i'd love to hear someones opinion on the matter
ReplyDeleteAlso thought on adding a exp pedal input to the control knob... i think it would get some weird and interesting sounds out off the pedal... specially in arpegiator mode
ReplyDeleteDidnt work for me i get low volume and nothing i do can fix it
ReplyDeleteit doesnt work well it needs a negative 3.3 power supply to work propperly i think i built it and is not working well
ReplyDeleteSomeone has verified this?
ReplyDelete1000 %
ReplyDeleteVerified
ReplyDeleteUpdate: replace potentiometer of 100k by 1k for correct operation of VOLUME, JOIN PIN 1 AND 2 OF CONTRO, DO NOT LEAVE
CONTROL PIN 1 IN SOLITARY
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DeleteWhat does this do though? It doesn't seem to make a difference either way.
Deletehttps://www.youtube.com/watch?v=gjJ7p9m8E3k&feature=youtu.be
ReplyDeleteNice! Thanks for verifying
DeleteHow much Ohms have you set on trimmer?
DeleteHi, do you think a HT8970 could also work? Cound find a HT8950. Thanks in advance!
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ReplyDeleteThis comment has been removed by the author.
ReplyDeleteHow much Ohms have you set on trimmer?
ReplyDeleteHi ! Thanks for the layout and thanks Dan for your advices !
ReplyDelete- I have set the trimmer at 3/4 , because at full level the noise is heavy, but this control is (for me) not usefull.
- Remove 470pF on output TL072 is a good way to have some trebles, I have put a switch between the two possibilities.
- I confirm that A1k for volume is necessary instead of A100k for a good range of control
- Instead of LM1117 I used a LM1086CT-3.3, same pinout.
This layout is OK for wire the 4P3T :
http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DBA/01-DBA_ROBOT_VERO.png
Simon
Many many thanks!!!
DeleteAnd what about normal mode, btw? In the wiring you gave link to there's two positions for arpegiator. I did everything like pictured.
DeleteHow do you wire the 3p4t?
ReplyDeleteHi all ! Someone has verified this one with the mod ?
ReplyDeleteI'll be trying with a rotary switch 1P4T in the right side of the HT8950 ...
Puede usarse con daisy chain?
ReplyDeleteHas anyone ever successfully added an expression input for "control"? I've been trying for a while, and it primarily just behaves like the pot is fully clock-wise (0 ohms basically) with only the tiniest sweep, as soon as you plug anything in. It's all crazy sensitive to interference. I even tried making a special trs cable with shielding between the wires, but to no avail.
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