mikepurvis

84 reputation

bio	website	uwmike.com
	location	Kitchener, Canada
	age
visits	member for	1 year, 6 months
	seen	Mar 13 at 17:02
stats	profile views	10

	84 reputation	bio	website	uwmike.com	visits	member for	1 year, 6 months
5 badges		location	Kitchener, Canada		seen	Mar 13 at 17:02

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Jul 17	comment	Sound card CD audio in connector Awesome, thanks! This is the horizontal version for others looking: octopart.com/70553-0003-molex-29645
Jul 17	accepted	Sound card CD audio in connector
Jul 16	asked	Sound card CD audio in connector
May 14	comment	How does CPLD propagation delay work? @scorpdaddy This is for precisely controlling deadtime in an H-bridge, as part of some experiments in audio. There are driver ICs which offer a dead-time control option, but it's usually pretty granular (select 5, 10, or 20ns). In the short term, I'm using DS1023s, but I'm curious to know in the future how possible it would be to generate a runtime-tunable delay some other (cheaper) way. The real question here is/was, if I can reliably generate the delay upstream of a cheap CPLD (by whatever means), can it pass through it with a consistent time offset?
May 11	comment	How does CPLD propagation delay work? @scorpdaddy That's great, though! All of those things are fixed at runtime except temperature, which has a maximum speed it is likely to vary at. If what you are saying is true, it's actually extremely deterministic. If such a system could periodically reverify its own calibration (say, at 1Hz), that would be more than enough to keep it accurate.
May 11	comment	How does CPLD propagation delay work? Right, but what circumstances would cause it to be better? "10ns or better" is not good enough when one is trying to exercise precise control. I'm trying to understand what factors would need to be controlled or calibrated for.
May 11	awarded	Commentator
May 11	comment	How does CPLD propagation delay work? I know that I can use one to implement something which depends on a clock (like I2C). The real meat of my question is, how dependable is that delay? I can build my circuit around an expectation that it will be 10ns, but are there factors would cause it to suddenly be 8ns or 5ns instead?
May 11	accepted	Is it practical to use separate MOSFETs for PWM and direction control?
May 11	asked	How does CPLD propagation delay work?
Apr 29	comment	Is it practical to use separate MOSFETs for PWM and direction control? Can you explain more about PWM linearity? Is this just due to ratios, or is it an inverse square thing, or something else? Is it something which could be compensated for in software?
Apr 29	comment	Is it practical to use separate MOSFETs for PWM and direction control? An XMOS device, either the L1 or L2. There are monolithic class D controller ICs, but they mostly start with an analog input, whereas I'd like to start with an SPDIF signal, do the crossover filtering digitally, etc. Part of the reason to be cost-sensitive on this aspect of the design is that I'm picturing it would be scalable to a system of 5 or even 7 powered speakers.
Apr 28	comment	Is it practical to use separate MOSFETs for PWM and direction control? It's true that audiophile stuff is often pricey. The idea of this project is to figure out how to build an all-digital DIY Class D amp that sounds great and is economical (so, no $40 FPGAs to do DSP stuff).
Apr 28	comment	Is it practical to use separate MOSFETs for PWM and direction control? The alternative isn't even necessarily four high-performance transistors—another option would be 2+2. Most low-cost designs use 1+1 in a half-bridge, but then you need a split supply, which has its own costs.
Apr 28	comment	Is it practical to use separate MOSFETs for PWM and direction control? Hi, thanks for your thoughts. I should have taken more care in the components I put forward for the example, so that it made more sense. (eg, the IRF6722 would probably be a more realistic choice for the PWM device).
Apr 28	revised	Is it practical to use separate MOSFETs for PWM and direction control? Adding more explanation of the application to amps.
Apr 28	asked	Is it practical to use separate MOSFETs for PWM and direction control?
Apr 14	accepted	Line level with respect to GND
Apr 14	comment	Line level with respect to GND Okay, this is really helpful, thanks. Is there any other reason (apart from it being linear) not to use a simple digital pot as a volume control? If I don't need a lot of resolution in the end application, can I just do the log conversion in software? (especially if I put a 1M and 5K unit in series) That might not be cheaper than an $8 IC, but I just want to consider my options.
Apr 14	revised	Line level with respect to GND Discovered part of answer on own.