Shuriken
-
Posts
973 -
Joined
-
Last visited
-
Days Won
11
Content Type
Profiles
Forums
Blogs
Gallery
Posts posted by Shuriken
-
-
Well, it was a ground loop.. sorry, I'm an idiot. Rewiring it w/ dual secondaries, two rectifiers basically made me clean up the grounding scheme. I rewired it last night as center tap w/ careful attention to grounding order, and it's quiet.
The unbalanced load definitely makes the volts coming out of the two halves of the transformer uneven, but the regulators fix that and it shouldn't cause noise.
New problem though... My 12v transformer along w/ my sagging home power (it drops about 10v when the air conditioning turns on) doesn't leave enough voltage for my 12v regulators, and they are noisy! When the AC is off, everything is quiet.
I guess I need a 15v transformer.
Yeah a 12V Transformer is cutting it very close (12V * 1.4 - 1.4 = 15,4V Rectified) That's almost exactly the 3 Volts the regulator needs to properly regulate. And that calculation doesn't take into account small fluctuations and deviations. My home power is not 230V but about 222V, the transformer output will also be slightly less. So a 15VAC transformer is what i use for a 12V linear regulator.
-
If you have a dual secundairy transformer, making a fake centertap is not a good idea. It is better, as you said, to use two bridge rectifiers.
The schematic on the wiki isn't great. First off all the LM79xx series need a bit of load (10mA) to regulate. Most schematics use a led with a 1k resistor. And it is best practice to put 2 diodes in for polarity protection.
For example:
The article on the wiki is probably in need of an update. nILS made a modular PSU where he did use diodes.
-
Not sure if I should hijack this, or start a new thread.. but my bipolar supply is a fail. I made it basically like what's on the wiki. http://www.midibox.org/dokuwiki/doku.php?id=bipolar_12v_psu&s
But, I don't have anything hooked to the negative supply right now, and it hums pretty bad. I think because the load is so unbalanced. I rewired it w/out the center tap (My transformer is a 2x12v, so I can wire it w/ or w/out a center tap) and made a unipolar positive supply, and it works perfectly.
Actually while typing this I think I thought of what to do, but maybe someone can tell me if I'm on the right track. I'll just use it as dual power supplies, using the two secondaries of the transformer individually.. no center tap. One positive supply, one negative supply, and connect the grounds together after the regulators. All it will cost me is another bridge rectifier. Does that sound correct?
Shuriken,
Someone on the DIY Audio forums made a PCB for the filament regulators. I believe the circuit would be the same for these.. I think the pinout and footprint is the same for the various regulators in the lm2267 line. (Double check, obviously).
http://www.neurochrome.com/audio/?page_id=361 There's a link to the PCB sales page on there.
Probably best to start a new one and then post your original schematic.
-
Ive made a switching supply, for tube filaments!! That's the last place you'd classically use one.. But it works very well! I used a lm22673. They have this awesome "webbench" tool that basically designs the circuit for you. http://www.ti.com/product/LM22673#toolssoftware Choose a good inductor and final capacitors, and you can get practically no ripple. The webbench tool will run simulations for you, to pick the best components for your voltage/current requirements.
I'm building a linear +/-12v and +9v and switching 5v supply right now for my 6582/filters.
Nice wicked1. I have all the components for a switching 6582 psu. Bought the lm22676 and lm22675. But havent gotten around to get some pcb made yet.
-
Good to hear you got it working. And also nice to see my Core32 is put to use :wink:
-
It gets to 98% then displays "Upload aborted due to error #4: Write failed (verify error or invalid address)"
What pic are you using the 18F452 or the 18F4685? and are you using the correct firmware for that pic?
-
Core and OPL3 should work. Without bankstick you should have 1 patch.
-
I have a 0.1" aluminum sheet I was hoping to cut and get a nice clean panel on the back for all the connections. Everything looks like it'll be flush, except the magjack, which sticks out. What have other people done to get this to look nice? I was thinking to just attach the magjack with wire a few mm off the board so I could push it back, then just JB weld (glue) it in my panel. Stupid idea?
An UTP connector is supposed to stick out, otherwise it is hard to get the connector out.
-
What, I haven't finished this yet? Weird! :whistle:
Well, it's mostly working and pretty much just needs some minor bugfixing and testing. How's your C?
A bit rusty. Maybe this wakeup call is just what it needs :wink:
-
** Taking into account that nILS is going to blame me for raising this topic from the dead :wink: **
I have a project (303-ish) which could really benefit from a small sequencer (a SEQ4L is too big tbh). Any chance this will release?
-
You don't have to use seppoman's SDCARD pcb for this. If you search for "arduino sd card" on ebay, You can find ready made ones. And looking for "stm32 ethernet" should give you the other one.
-
Tim, thanks for all your efforts supporting this community. It is much appreciated. I cannot help feel this was a forced move and not entirely your own choice.
I read a couple of your responses on this. I can imagine this has been a rather frustrating undertaking. Having 100+ people on the waiting list. Lot's of people not responding....Meanwhile not wanting to gamble your life savings on this.
-
What does the datasheet tell you? :whistle:
-
Maybe it can be done with a stepup dc-dc converter. But it would be complex.
-
I had a look but can't find any older versions. I have version 1.1 in my personal download archive. But i don't think that would go well with the Sammichfm.
-
I have been reading Wilba's mb-6582 construction guide this afternoon. there are several embedded links in the text that refer to specific threads in the forum. The URL's in these links look like this:
http://midibox.org/forums/forum/index.php/topic,9623.msg70697.html#msg70697
i am assuming that they used to work? I have tried three different browsers, all with the same result: I just land on the front page of the forum section when i click on one of these links.
Does anyone have a tip on how to make these work? Am i just being a dim-wit and missing something simple? Thanks for your help.
These links are from the old forum software. They don't work anymore. The posts are still there. Maybe you can find it with the Search option. Also there is a great from Hawkeye which might be helpfull for you.
-
Why don't you have a look at the schematic of the Core32 (STM32 based)? Midi Out looks the same to me.
-
I have two STM32 based Cores laying around. One is almost completely build. The other one is in unopened antistatic packaging as received from smash. Let me know if you are interested.
-
Oh yeah, good one. I forgot about that site.
P.S. the title should say: Decent 19inch case :wink:
-
Does anybody have a recommendation on a reasonable price/quality rack case in europe?
I bought some at www.pollin.de they are horrible. I think they are the same ones that banzai sells. They look the same as this picture that Rosch posted. All crooked and you have to bolt all the panels together.
-
I ordered one at iprototype.nl...let's see if it is a good substitute.
Update:
I received it today.
Physically fits perfectly and the specs it seems to be pretty similar.
-
-
In Europe it's not uncommon to do a bank transfer. But then it is relatively easy and without any cost nowadays. In this case it sounds like it's easier to use paypal.
-
no match on mouser for THAT300P14-U
how did you found it Shuriken ?
Brathering where do you ship from?
Cheers
Mouser partnr: 887-300P14-U
Hoeveel nedrlanders zijn er eigenlijk actief ?
in Nederlands
Posted
Nee zijn opzich niet kant en klaar beschikbaar. Waar zat je uberhaupt aan te denken? want midibox is een breed begrip.