mirmite
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« on: March 10, 2012, 12:04:39 PM » |
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hi! have been looking for a good 8 step sequencer for cv uses,
Have found alot of schematics but no pcb or eagle file. anyone have one laying around =?
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mikebike
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« Reply #2 on: March 11, 2012, 02:06:18 PM » |
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Your link is for the dual ADSR, colin?
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expanoncolin
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« Reply #3 on: March 11, 2012, 09:03:04 PM » |
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mirmite
phpBB Junior Member
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« Reply #4 on: March 21, 2012, 01:39:54 PM » |
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oh love the MFOS Ten Step Analog Sequencer.
But i shuld start out a little smaler, was thinking of a singel sided deisng maby 8 steps, that i could etch out at home
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hogohogo
phpBB Junior Member
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« Reply #5 on: March 26, 2012, 01:23:06 PM » |
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Hi Mirmit, recently i bought this one at eBay- Germany. Look here: http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=270905939339 Its a very nice 2*8 Step CV sequencer based on a NE555 and 4 4051 CMOS- counters. I uploaded the instructions (in german) including schematics and a picture of the Sequencer i assembled to : http://dl.dropbox.com/u/2982241/ElradSequencer.pdf It also includes PCB outlines if you want to make your own PCB. Its intended for a standalone unit, but im sure you can also bring to a module. At the moment i am experimenting to get external clock working with it. I also added PWM for variable gate times. Greetz Thomas |
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« Last Edit: March 26, 2012, 01:46:28 PM by hogohogo »
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endorphin
phpBB Junior Member
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« Reply #6 on: December 22, 2012, 09:13:26 PM » |
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Hey I just ordered all the components for the MFOS 10-Step Sequencer. Should be here any day now. It'll be my first attempt at a double sided etch, but I imagine it shouldn't be that difficult. I have an old ethernet hub as my enclosure which has already been repainted. Also I am making a design/labeling to screen print hopefully tomorrow. I just realized that I need to build a dual power supply -12 +12 and Ground. Could anyone suggest a good one that I can build. It would only have to supply the 10 step sequencer. I'll post pics of the build in the next couple of days!  |
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expanoncolin
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« Reply #7 on: December 28, 2012, 09:24:55 AM » |
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The simplest thing would be to just buy a +/- 12V supply. Otherwise, you can build something like this:  Note that if you use an AC adapter (120V to, say, 18V AC) you can omit the transformer on the right - that's the AC adapter! You will need to use 7912 and 7812 chips. -Colin |
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endorphin
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« Reply #8 on: January 05, 2013, 08:35:34 PM » |
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Did you mean the transformer on the left? Labeled T1? Well I'd like to use a 12V AC adapter or "wallwart" as most people seem to call them on forums, I thought I'd use the layout from MFOS specifically for using an AC wallwart and etch it on a pcb. Is this schematic more or less the same? Minus the variable output voltage. Have you tried the MFOS bipolar power supply. I'd happily use this one shown above, it seems like less parts. Maybe I'll work out a layout on stripboard. Regarding the transformer, I have a 12V DC adapter. Would I be able to convert the output to AC? I thought maybe by removing the Diode Bridge Rectifier which would literally be the diodes or the DIP package. Would this work?  I just thought about this, lifting the negative voltage from the diode bridge because it is not being used? |
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« Last Edit: January 06, 2013, 02:24:18 AM by endorphin »
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endorphin
phpBB Junior Member
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« Reply #10 on: January 06, 2013, 07:41:20 PM » |
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Looking at the diagram above, is that transformer center tapped? I've been looking up transformers and diode bridges all day  and in that configuration with a center tapped transformer the diode bridge takes in AC voltage and puts out a + and - voltage? Positive to the lm7812 and negative to the lm7912? Where as in the MFOS power supply both Regulators are powered from the Positive AC side? The diode configuration in that circuit doesn't look like a diode bridge to me am I correct? |
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expanoncolin
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« Reply #11 on: January 07, 2013, 02:37:07 PM » |
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Lots of questions! You need +/- 12V DC. You can get this either by buying a +/- 12V DC power supply, or buying a 12V AC power supply and using to generate +/- 12V DC. The schematic I posted is for the latter choice. I meant to refer to the transformer on the left, T1, as you say, sorry! No, you can't use your 12V DC power supply. You also need -12V. The link you posted just links to the general MFOS page - if you were referring to http://www.musicfromouterspace.com/analogsynth_new/WALLWARTSUPPLY/WALLWARTSUPPLY.php I would HIGHLY recommend reading that and following those directions. It is a very thorough discussion of how to build exactly what you need. -Colin |
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endorphin
phpBB Junior Member
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« Reply #12 on: January 07, 2013, 03:28:09 PM » |
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Yes lots of questions! I am very eager to learn and understand both the schematics as I will be using them now and in the future. I've read the all of the information and directions many times now so I feel I have a good enough understanding and confidence to build them.
Buy one? All I could find were bipolar computer power supplies that seem huge and pricey. I am here to build anyways man! I have to at least attempt it....
So I ordered parts to build both of the power supplies that is the one you posted and the MFOS supply. And I do still intend to post pics of the build progress, but perhaps in a new thread though.
I still have a question about that transformer though, it is of course a step down transformer but center tapped and that is where ground goes to?
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