Frequency central PSUs?

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White noiz
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Frequency central PSUs?

Post by White noiz » Tue Oct 15, 2019 5:34 pm

I am planning on building a 104hp 6u rack with approximately 24 modules. Would 2 routemaster psus be better than than 2 microbus PSUs to power the whole rack? A routemaster will be able to supply more power right? Cheers.

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Noodle Twister
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Post by Noodle Twister » Tue Oct 15, 2019 6:48 pm

Route master may be a better choice because the power headers have a greater distance between them. As far as I'm aware both routemaster and microbus supply 500ma positive and 500ma negative plus 100ma on the 5V.

One of either could be enough to power 104hp 3U but it depends on the power demands of the modules that will be drawing from it.

If your thinking of a lot of digital modules then 100ma on the 5V isn't really a lot.

White noiz
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Post by White noiz » Wed Oct 16, 2019 10:46 am

Thanks for the info. Yep, think im going to go with the routemaster and if more power is needed i'll add a microbus or 2.

How come they both only supply 500ma the regulators on both boards are rated at 1.5 amps? :tu:

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Agawell
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Post by Agawell » Wed Oct 16, 2019 12:05 pm

they only supply 500mA per rail because FC recommend using a 1A 12vAC wall wart to power them

if you suspect you'll need more than 200mA of 5v in the case then I'd look at a different solution - perhaps one of the befaco DIY boards

you may also want to look at linking the grounds
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Severed head
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Post by Severed head » Wed Oct 16, 2019 12:21 pm

depending on your power specs and if you've got components on hand after all the added shipping from 2 outlet you may be better off to just go with the old trusty TTA uZeus W/ an extra FBB or 2. that is if your not 100% dedicated to DIY

White noiz
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Post by White noiz » Wed Oct 16, 2019 12:43 pm

Thanks guys. I've got a 3amp ac/ac adapter laying around and thought I could just put a huge heatsink on each of the 12v regulators and get more current out of the regulators. I dont plan on using any 5v modules at the moment, never know though, ha. Think im gunna stick to the fc pcbs as money is going to be tight for a while! :hyper: :hihi: :tu:

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Noodle Twister
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Post by Noodle Twister » Wed Oct 16, 2019 1:20 pm

Frequency central is a good choice of PSU for starting a small setup.

Later on you can use it as a bench power source for testing modules you have DIY'ed if you like and make something bigger.

For a second step into DIY with more power you could keep an eye on the for sale/trade thread on here for a low cost Doepfer case.

Alternatively I would be looking at something like this as Agawell suggested



https://www.thonk.co.uk/shop/befaco-excalibus-kit/

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Post by White noiz » Wed Oct 16, 2019 4:18 pm

I like the look of that befaco. Plenty of power and headers.

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OB1
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Post by OB1 » Thu Oct 17, 2019 4:54 am

I have lots of Routemasters and I use them 1 per 3U/104hp. They can supply more than 500mA per rail. The Voltage regulators are rated at 1.5A, but you would need LARGE heatsinks if you plan to use all of that. I run mine with relatively small heatsinks and use 2A wall warts with them with no problems.

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Synthbuilder
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Post by Synthbuilder » Thu Oct 17, 2019 12:19 pm

With a 1A wallwart the best you can get is closer to 280mA per rail. Taking 500mA from each 12V rail would take around 1.8A from a wallwart which would probably buzz and get rather hot.

The best thing to do is measure the AC current with a true RMS current meter. You'll find it's not a direct one to one relationship for DC load and secondary current. It's more like a factor of just under two, and given that one is driving two rails with one single phase AC input, the wallwart's output current is likely to be closer to four times that of the current taken by each rail.

So even with a 3A wallwart you shouldn't really be trying to take more than 750mA from each rail.

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EATyourGUITAR
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Post by EATyourGUITAR » Thu Oct 17, 2019 2:10 pm

The "grounds" will link as soon as you patch your first patch cable between rows. How much current travels between modules on patch cables through 100K resistors. Answer not much. There is no harm in connecting all the 0v together but also no benefit. If you decide to have mains earthed 0v then they will all be connected through mains earth. You should only earth your bus board if you understand how this makes you more or less save if some situations. The less important consideration would be about ground loops and also USB devices interfacing eurorack. All desktop computers have mains earth referenced USB power. You could be in for some hum.
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White noiz
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Post by White noiz » Thu Oct 17, 2019 4:13 pm

Cheers. Will try and push the routemaster with taller/bigger heatsinks and see what happens. I'll be happy if i can get 750ma. Will i get voltage ripple if I push the regs more?

Do you have many problems with noise/hum with the routemasters OB1?

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OB1
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Post by OB1 » Fri Oct 18, 2019 4:15 am

White noiz wrote:Cheers. Will try and push the routemaster with taller/bigger heatsinks and see what happens. I'll be happy if i can get 750ma. Will i get voltage ripple if I push the regs more?

Do you have many problems with noise/hum with the routemasters OB1?
No, they're really quiet. Across my cases I have a mix of Routemasters, Mean Well RT-65bs and one Doepfer PSU. The Routemasters are the quietest by far.

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thealienthing
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Post by thealienthing » Fri Oct 18, 2019 11:38 am

Joining in this convo. Sorry for the noob question. I just built an FC power supply for my first DIY dive into eurorack. I just wanted to add ask what y'all would recommend for testing the power supply. I've checked with my multimeter to make sure that I'm getting +12/-12 and +5 from the unit and it's all looking good. I have not yet made my first module, but I have have a behringer model D which is eurorack compatible, but I'm nervous to plug it in until I'm sure the power supply won't fry it.

Are there any other viable tests I can do beside the multimeter test to make sure my power supply is fry proof? If there isn't, I'll probably just wait to test it until i make my first module which is going to be a simple VCO. But I appreciate any input y'all have.

White noiz
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Post by White noiz » Sun Oct 20, 2019 2:41 pm

Thanks OB1. Appreciate the advice.

thealienthing, Best thing is to post a picture of your work. If you've done it all correctly you wont have a problem. But, will the fc power run the MD properly? it comes with a 1 amp psu out of the box right?

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