Blacet Scanner options

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diophantine
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Blacet Scanner options

Post by diophantine » Wed Feb 01, 2012 8:35 pm

I sent an email to Blacet last week about the various trimpots and such described in the documentation, along with a few even more benign questions, but got a sadly terse answer back that they don't offer support for any mods. :roll:

Anyhow, hopefully some of you you can help me out!!

Basically, I'm planning on building a Blacet 2600 Scanner into MU/Dotcom format. The online manual is here:
http://www.blacet.com/MD26XXmanualBasic.pdf
I want to plan out my panel in advance. Unfortunately, the manual is for both the Scanner and Sequential Switch, so I don't know what applies to what, and some isn't entirely clear.

I plan to move trimpot RT2 (Dither) to a front panel pot, to allow me to adjust the overlap between inputs while scanning.

Besides that, I've got 2 questions:

1. Trimpot RT1 (Ref) apparently adjusts the voltage at which the Scanner with switch from input n to n+1. What I'm wondering is, does this loop around? I.e. if you set it to switch at .333 volts, will you go back to input 1 at 1V, input 2 at 1.33V, input 3 at 1.67V, etc.? Basically, is it looping, modulo-wise, or when it hits .67V will it stay on input 3 no matter how high the voltage goes?

2. The documentation also mentions a DIP switch, to give it a 4th "off" (0V, presumably) stage. Is this just for the sequential switch, or for the scanner too? And, if it is part of the scanner, how does it interact with RT1 (Ref)? i.e. if RT1 is set to a switching point of .333V, will enabling the DIP switch change it to .25V, or will stage 4 (0V) be triggered once the input voltage reaches 1V?

Also, and marginally off-topic, I understand that most Blacet modules operate in a 10Vpp range, audio-wise, but I'm curious what the standard CV range is: 0-5V (like most 5U stuff), or 0-10V (like many Euro things)?
Last edited by diophantine on Wed Feb 01, 2012 8:38 pm, edited 1 time in total.

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e-grad
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Post by e-grad » Thu Feb 02, 2012 5:26 am

The Seq Swith loops the Scanner does not loop. The latter has no DIP switch to select the number of stages, either.

You might be interested in the
MD2600 Scanner Mods
you'll find here:
http://blacet.com/tech.html

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fracmonkey
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Post by fracmonkey » Thu Feb 02, 2012 11:42 am

Looks like those mods are now "production" standard.

The CV range input is adjustable with the trimmer. On mine, FCCW needs 9V to select "C". Midrange on the trimmer needs 5V to hit "C".

Nice module; could use some LEDs. Probably easy to add.

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e-grad
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Post by e-grad » Thu Feb 02, 2012 11:58 am

fracmonkey wrote:could use some LEDs.
True.

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diophantine
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Post by diophantine » Thu Feb 02, 2012 11:59 am

Thanks for this info! Great to know!

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fracmonkey
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Post by fracmonkey » Thu Feb 02, 2012 5:16 pm

Adding LEDs to the Blacet Scanner.

All you need are three ultrabrite/low current red LEDs and a 3.3K resistor. The LM3914 outputs go low when active.

The photos should tell the rest of the story. I used a hot melt glue gun to hold the LEDs and 24 ga solid wire. The right end of the 3.3K resistor goes to the +15V buss. Extra credit: How many mA does each LED draw?
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idiotunderground
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Post by idiotunderground » Thu Aug 09, 2012 3:27 pm

fracmonkey wrote:Adding LEDs to the Blacet Scanner.

All you need are three ultrabrite/low current red LEDs and a 3.3K resistor. The LM3914 outputs go low when active.

The photos should tell the rest of the story. I used a hot melt glue gun to hold the LEDs and 24 ga solid wire. The right end of the 3.3K resistor goes to the +15V buss. Extra credit: How many mA does each LED draw?
tried adding LEDs to scanner using the method descibed above, no go. module still works as it should but no light action. hooked up three wires from the back of RN1 on the PCB to LEDs, connected all ground together and over via 3.3K resistor. am i missing something?

i've already done the mods to the sequential switch (including added LEDs) described here viewtopic.php?t=211&postdays=0&postorder=asc&start=40 on the seq switch you've got to use a resistor for each LED, anyone know if i should i try this method for the scanner instead?

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fracmonkey
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Post by fracmonkey » Fri Aug 10, 2012 8:30 am

Maybe you have the LEDs backwards?

idiotunderground
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Post by idiotunderground » Fri Aug 10, 2012 11:47 am

:doh: fixed

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fracmonkey
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Discontinued

Post by fracmonkey » Thu Oct 26, 2017 2:45 pm

Eight kits left. No more will be made. Free mod parts if you ask when ordering. I did mine. Now I get whatz going on!

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Post by diophantine » Sat Oct 28, 2017 8:13 pm

Got my kit today and built it with the LED mods! Haven't actually patched it up, but everything appears to be working fine. One thing I didn't realize is that there is an "off" position on the Scanner, before it hits the 'A' input, which is actually pretty neat. Makes it more of a VC Scanner/VC [non-sequential] Switch combo. Easy to disable by just moving the knob up a bit 'til the 'A' LED lights up.

My Roper-Whitney punch made just sliiiiightly too big a hole for the LEDs. Some T1 LEDs have more of a lip than others, but the ones I used just barely slipped through the holes. If I were to do it over I'd use a smaller punch and ream/drill the holes until they were perfect. Obviously not problematic, but just made the project take a little longer. I put some dabs of hot glue (ok, one is more than "a dab") on to hold them in the correct place, and then finished them off with Elmer's, like I usually do with LEDs. Not completely dry, but it was dry enough for me to solder up the LEDs.

I thought about installing a tiny pot for the dither control, but I don't think I'll do it - would seem a bit crowded IMO. From what I can tell from the schematic, it really just changes it from A/B/C to A/A+B/B/B+C/C, where the dither controls the size of the '+' regions. If I were to do a mod it would probably be to replace/augment the trimpot with a few resistors and a front panel switch to switch it between those modes, where the '+' mode has all the regions the same size. ** EDIT ** After reading the circuit description, I think I may be wrong. ***

Anyhow, really looking forward to trying this out. I imagine running a Binary Zone to the CV input could produce some rather interesting results.

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diophantine
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Post by diophantine » Sun Oct 29, 2017 2:07 pm

Follow-up to my edit above, after I managed to clear a path into the studio... It does do a cross-fade, but the trim-pot is more of a set-and-forget type thing, and I don't imagine it would get much use as a panel pot. With audio signals the switching can be somewhat jarring when the dither trimpot is set to 0. Trimmed it by ear to around 11:00 where the transition is pretty smooth without being exaggerated.

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fracmonkey
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Final Units

Post by fracmonkey » Thu Dec 14, 2017 9:13 am

The last seven kits were bagged up yesterday. Six remain. Final run of this module.

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