photos of the delta1

delta1

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Re: photos of the delta1

Postby mattcalf » June 19th, 2010, 7:41 pm

Loving all the updates linuxworks! :)

If the last relay is used for I/O, isn't that intruding on the delta2's functionality?

Cheers,
Matt.
amb wrote: Like a pure class A amp should, the maximum heat dissipation occurs when the amp is idle. It will actually run cooler when playing loud.
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Re: photos of the delta1

Postby linux-works » June 19th, 2010, 7:55 pm

mattcalf wrote:If the last relay is used for I/O, isn't that intruding on the delta2's functionality?


a little bit, yes. but if you have room for the d2, that's great. you can then assign the 8 ports to ins and outs as you choose.

but if you need only 1 A/B selector (an input or output) and are also doing a 7bit or less build, there's no real reason why you can't make use of hardware that's 'just sitting there doing nothing' ;)

you do need to take one of the relays and mount it on a small perf board. I will probably use a pair of KK's (like the d1 and d2 use) to connect the rear 2 jacks to the board. the jacks and board take up more bulk than the single relay does but that's the way it goes. the little board just becomes a 'break-out' board for a single floating relay.

I plan to make the software configurable so you can assign that 8th relay (the floating one) to be an input select or output select. if its an output select, then it will be just a logical switch that gives power to some larger relay, capable of handling speaker level power. if its an input select, then the little omron latchers are fine for that and so it can be directly in the signal path and just 'remoted' to be near the input jacks, themselves.

if you are doing a full 8bit build then you have no spare relays on the d1 board and you must use a d2 i/o system to do your ins and outs.

I think I'll have 2 test cases that I'll build. my b22 is more of a phones/speaker amp and so that LCDuino system will have its 8th relay act as an OUTPUT selector. my small hammond black metal box is just a standalone passive attenuator and so maybe I'll add a 2nd input jack and make that one the test box for the INPUT selector.

if you need both input and output, at that point you really do need to get the d2 system and stop taking short-cuts like this '8th relay hack'.

but I do think the 8th relay hack will have a place and some use in some of the installs.

btw, you will be able to pick how this works at run-time. I'm working on some menuing system for the LCD1 that will let you set config 'variables' from the IR remote and the display, sort of like how windows has a 'regedit' to edit the registry. the LCD1 has a registry (tunable and settable things) and I'm trying to get this user-accessible via the regular remote and a button to get into this mode. once that is all working, you'll enter the 'registry edit' mode, change the mode from '7bit' to '7bit + input' (or something like that) and it will then know to assign that high bit to the input_select function.
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Re: photos of the delta1

Postby fishski13 » June 19th, 2010, 11:05 pm

the boards must be pretty small, because until closer inspection, i thought the resistors were RN60 :ugeek: to L.M., it's also nice to see a a healthy amount of solder on the pads :geek: .
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Re: photos of the delta1

Postby mattcalf » June 20th, 2010, 2:24 am

Very cool, Linux. Thanks for the very informative reply, and the extra functionality you're always adding! :)
amb wrote: Like a pure class A amp should, the maximum heat dissipation occurs when the amp is idle. It will actually run cooler when playing loud.
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Re: photos of the delta1

Postby mattcalf » June 21st, 2010, 6:10 pm

Had a thought the other night, how many relays (on the d1 or d2) would have to be sacrificed to offer a variable gain?

Cheers,
Matt.
amb wrote: Like a pure class A amp should, the maximum heat dissipation occurs when the amp is idle. It will actually run cooler when playing loud.
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Re: photos of the delta1

Postby linux-works » June 21st, 2010, 6:53 pm

more updates ;)

my i/o board (input, really) works. I like it ;) sure, it crams tightly into the hammond but that's ok.

Image

bottom of the pc board that holds the 2 input TRS jacks, the DPDT latching relay and 2 molexes (1 for relay trigger and one for L/R selected input):

Image

top of same board:

Image

the molex closest to the relay is the set/reset trigger pair (coil pair). the molex header on the board to the left is the L/R selected pair. the jack on its own to the far left is the output TRS jack and it has its own pair of L and R wires coming directly from it.

of course, if I wanted an output selector, just get hold of a mirror, hold it next to your computer monitor with this image showing and use that as a wiring guide. (j/k).

yes, I'm using a lot of TRS jacks for my analog gear. I like how its a single jack, a single cable and no left/right mixups. very neat for DIY. I know crosstalk will *measure* worse but you won't hear the diff. at least I don't ;)


the input board was definitely an afterthought! I would not normally mount a board like this.

(hey, who am I kidding. I mount stuff like this every time, all day long. lol)


I'd say its a great use of a 'spare' relay and the ULN driver gates and 1/8 of the 2 PE chips. too much dead silicon not to be put to better use ;)
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Re: photos of the delta1

Postby linux-works » June 21st, 2010, 7:03 pm

mattcalf wrote:Had a thought the other night, how many relays (on the d1 or d2) would have to be sacrificed to offer a variable gain?


on what amp? where? where's the gain stage?

one thing that I tossed around a few times was having a truly switchable gain stage that you could 'call on' when you wanted. just a before/after tap on the gain stage would let you bypass (truly) or run thru it. then, if the gain stage gave you 10dB, say, the lcduino could even take that into account and add 10 to the dB figure (or not) if the gain stage is switched in.

one could argue that its more effort and you might as well just always leave the gain stage (or buffer) connected. I'm not sure if its obvious one way or the other, but I like giving options if it does not cost much (and its just software, so its not a parts-cost).

if you want to switch a single gain stage in and out, that's one DPDT relay.

if you wanted to switch a programmable gain amp (like a 1/2/4/8 progression on a feedback gain programming R, say) then you could allocate some of the relays toward this function and if you got into a mode where you vary the gain, you'd manipulate only those bits and leave the rest (attenuating bits) alone. it would be custom/edited firmware but its not too too hard to do stuff like that.

a diff project entirely, but I have thought about using LDR's as programmable 'gain control' elements in, say, an M3 and having the lcduino dial in various R values via the LDR to set the M3's gain. I still want to do that, someday.
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Re: photos of the delta1

Postby mattcalf » June 21st, 2010, 8:19 pm

The M^3 specifically and a balanced one at that.

Thanks for the explanation, I can say I follow it all though. :)
amb wrote: Like a pure class A amp should, the maximum heat dissipation occurs when the amp is idle. It will actually run cooler when playing loud.
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looking at the 5v digital rail while clicking the relays

Postby linux-works » February 25th, 2011, 3:56 pm

testing out the effect of the relays on the digital 5v power supply. I am playing with a different relay firing method and want to see if it brings down the Vcc line much.

Image

the scale is 10mv per vertical div and there's about 37mv of drop from 5.04v out of the 7805 regulator.

the input is somewhat weak, its a DC wall wart (feeding dc into the s25 bridge, so we already lose some voltage there) at about 7.5v and its rated at 600ma. this is a pretty low end wall wart but at least its a linear type.

the scope is ac-coupled to look at the noise. the fuzz you see that's about 5mv or so seems to be from the rigol scope, itself. shorting the probe to ground gives about the same level of fuzz, so I don't think its the regulator output that is noisy. what is real is the square waves that happen when you run up or down the relays.

is 0.037 volts enough to care about? no, I don't think so. my previous power supply was giving me less than 5v out (4.8 or so) and I was still able to run but I was noticing some relay sticking under heavy activity. bringing it to 5v cured that. lesson to take away is: make sure you have a pretty stable 5v and not 4.7 or 4.8v ;) as long as its 5v and does not drop too low, the relays should fire just fine. if you find relays are sticking, check your Vcc and see if it bounces too much.
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Re: photos of the delta1

Postby linux-works » February 25th, 2011, 8:35 pm

Image

top line is one of the analog lines (12v) that supplies the a20 buffers. bottom line is the 5v 7805 digital supply.

you can see where the relays are pulsed, then relaxed, then the other side is pulsed and then relaxed. then some delay (auto-repeat time on IR keypad) and then more relay pulses if the vol value changed.

some fun with my new scope watching the click algorithm, I guess ;)
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