The Thomas Henry Mega Percussive Synthesizer

[hendrixworkshop]

[Uncle Krunkus]

Yep, that'll do it.

[hendrixworkshop]

Thanks very much uncle krunkus!!

Ordered most of the parts today, and now I'll have the power supply taken care of! There will be 1 more of these on ebay now.

More questions soon I'm sure.

[Uncle Krunkus]

[hendrixworkshop]

Yes. Sorry I wasn't clear.

There is one more of the same PSU I mentioned two entries back on ebay now. Item number: 200299107095

[hendrixworkshop]

>>Under the heading (at the bottom right of the parts list pg) -

What is the difference between the 1/4" jack needed for J1-J6, and the ones needed for J7-J10?

I assume they should all be closed jacks - I just don't know what the "n.o." and "n.c." mean.

[magman]

You can get jack sockets with switching contacts built into them.

N.O. means Normally Open, which means that with no jack inserted in the socket the "Normal" state is for no connection between the switching contacts. When you insert a jack into the socket, this will change. It is a bit unusual to have N.O. switches in jack sockets, but you can get some sockets to do this (with changeover contacts). For the MPS though, looking at the circuit diagrams, it just means you can used an un-switched socket, or not bother with the switched connection if you're using the same jack type for all connectors.

N.C. means Normally Closed, which means that with no Jack inserted in the socket, the "Normal" state is for a connection between the switching contacts. This is a more common occurrence, it is used to "Normal" a connection so that with no jack inserted in the socket, a default connection is already made.

If you look at sheet 4 of the MPS circuit diagrams, using J8 as an example, with no Jack inserted the "n.c." aspect of the socket will take the signal from C26 as an input to the mixer, or you can manually patch another signal into J8 instead, ignoring the input from C26.



Here's an image of a switched open frame jack from the Maplin website.

Hope this helps.

Regards

Magman

[hendrixworkshop]

Thanks Magman for your response.

So a Normally Open jack could be a Switchcraft Mono jack & a Normally Closed jack could be a Switchcraft 12A Shorting jack?

[magman]

Yep, it looks like they would fit the bill very well.

Regards

Magman

[bugbrand]

Just going back to the HEADERS...

You can also get IDC (Insulated Displacement Connectors) types where you don't need a crimp tool (you still are meant to use a little metal insertion tool though). I started using them recently and they're a LOT quicker than the Futurlec headers.

Trying to find the right ones can, as is often the case, be a bit of a head-scratcher due to suppliers having SO many different types of ....things....

But search for MTA100, for example at Mouser
http://gb.mouser.com/catalog/638/1391.pdf (that's the catalogue page)
Note that they have different ones for different gauge wire too.. (just to confuse even more!)

---

PowerConnect_1.jpg
Description:	Here's a pic of the 'old' type and the new (red) MTA100 connectors.
Filesize:	35.86 KB
Viewed:	325 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

---

[hendrixworkshop]

Bugbrand,

Thanks for the header info. It helps alot.

By the way - what is the wire size you used for this build?

Andy

[hendrixworkshop]

Sorry for the last question about wire size. When I opened the Mouser catalog page I saw that the color of the connector is indicative of the the wire size used.

Thanks again bugbrand for the info.

Andy

[rumpofsteelskin]

is there a particular XR2206 that needs to be used for this? I had a look on ebay and i found the following ones...

XR2206CP
XR2206CN
XR2206M

Some are cheaper than others, by quite a long way. Does this design require a particular type? I would be interested in buying the cheapest one necessary

I assume that these are MOSFET varieties?? what do the post-fixes mean?

[hendrixworkshop]

As I get closer to having all my parts ordered, I noticed on the bug brand wiring diagram "MPS Panel - rear view" that some of the pots are audio taper ("A" -- all the Decay, Noise, Shell & Impact pots). AM I right?

The Parts list indicates all pots should be linear. I'm inclined to believe the bugbrand diagram, but I figured there would be a revised parts list if that were the case.

Also the parts list calls for 6 - 1/4" phone jacks normally open, and 4 - 1/4" phone jacks normally closed. On the diagram, there are only 4 jacks present. I feel like I'm missing something again : )

Could someone set me straight?

[hendrixworkshop]

Sorry. I should have reposted the doc I was speaking of from bugbrand. It is somewhere in the thread, but here it is again.

Andy

---

mps_connections_v1_133-2.pdf
Description:		Download (listen)
Filename:	mps_connections_v1_133-2.pdf
Filesize:	931.23 KB
Downloaded:	518 Time(s)

---

[Uncle Krunkus]

Bug used audio taper for all the mixer pots and decay pots. Not a bad idea, but not absolutely neccessary. Do it if you've got em. I used linear all round, and can still dial in what I want.
Thomas included the option of a "Send/Receive" style pair of jacks for each partial before they hit the mixer. Bug didn't include them, he just wired straight through. I would actually do the same if I did it again, as I don't use mine at all. There could be anything from 3 to 11 jacks depending on what options you have the space to include.
Any XR2206 should work just fine. The suffixes are makers codes I think.

[hendrixworkshop]

Sorry for my ignorance.

I have a couple of questions:

On the parts list, C1 and C2 -- All I could find at Jameco were 820pF Ceramics / also I don't know what a poly looks like. Does it matter?

On the parts list, C4 - C12 that calls for 0.01uF disc (I'm assuming that that means ceramic disc). Can mylar caps be substituted?

Board is populated, except for these components.

Cheers,

Andy

[Uncle Krunkus]

820pF ceramics should be fine. The standard Poly(ester) is the "greencap", but MKT box caps are a bit better AFAIK.
Yep, disc is a ceramic disc, and mylar would be fine.

BTW, except for a few specific cases, the main thing to check with caps is the value, followed by the voltage rating, followed by their physical size (ie, do they fit in the PCB holes?), then worry about the type.
Most of the time, the value will dictate the type, or at least narrow the field to just 2 or maybe 3 possible types. By the time you take into account lead spacing and voltage rating, there aren't many choices left.

[hendrixworkshop]

As far as the caps all being 16v...

Does the voltage matter as long as it is more/higher than 16v - say, 100v?

Thanks again!

I'm obviously a "connect-the-dot" builder, who doesn't know much about electronics. I'm trying to plow through with your help. I really appreciate everyone's help.

[Uncle Krunkus]

Yeah, cap voltage ratings just need to be at least as high as the maximum voltage they are likely to experience. Most cases, the supply voltage. Add 15% to it and go for the next voltage rating above that or beyond, but not below.

[hendrixworkshop]

Thanks a lot for getting back to me so fast. I'm getting off work early and picking up the rest of the caps locally.

Thanks!!

[hendrixworkshop]

I'm assuming that on the pcb, where the headers go - that pin 1 is always the square marked hole. Could someone take a gander at the merge I did of the pcb shot and the bugbrand mps_connections chart.

I appreciate it, and I hope , if it's right, that it will be helpful to others.

Thanks,

Andy

---

MPS layout.jpg
Description:
Filesize:	290.42 KB
Viewed:	598 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

---

[hendrixworkshop]

When I went out to finish the wiring last night, I realized that I photoshop'ed my question on a shot of a prototype board. Sorry. The main question still applies though.

Thanks!

[Uncle Krunkus]

Yeah, it looks like it would be very handy. Just ignore the two optional CV ins on the header in the middle of the board, they're not on the final release.

[hendrixworkshop]