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Test Equipment / Re: Firmware update for Gratten ADS1102CAL+ oscilloscope
« Last post by tv84 on Today at 11:56:00 am »This is the only Atten CAL+ FW I ever saw.
Don't know what version it is.
Don't know what version it is.
Recent Posts
2
Repair / Help repairing Klipsch KDA amplifier power supply and identifying smd component
« Last post by r2digital on Today at 11:52:41 am »Hello, I Have a klipsch KDA500 amplifier that has a bad power supply. It turns on after about 10 attempts but im barely getting any voltage on the -13 volt rail. I have compared voltages to a working KDA1000 with the same power supply and this is what i got. Picture with the purple line shows where the trace starts at the yellow wire and ends at the negative trace of capacitor 35v 47U capacitor and should be -13-14VDC
kda500 power supply {not working properly}
right to left
4 pin
brown 8.06
black 7.93
white -0.11
gray -0.10
5 pin
green 30.16
blue 3.29
green 2.58
red/white 3.01
red 1.11
3 pin
yellow -.759 <—— this should be -13-15VDC
light blue -0.024
yellow 13.78
3 pin
black 165
brown -166
red -165
Kda1000 operating normally
4 pin
brown 8.52
black 8.92
white -0.003
gray - 0.003
5 pin
green 32
blue 3.33
green 2.6
red/white 3.05
red 1.1
3 pin
yellow -13.7
light blue 0
yellow 13.8
3 pin
black 157.5
brown -157.8
red -157.8
55bz<—- need help identifying what this is as it is not giving me proper voltages
these are the measurements from the working power supply on the 55BZ smd component
1 -18.2
2 -18.2
3 -5.83
4 -18.71
5 -18.71
6 -18.71
The measurements from the non working power supply 55BZ chip
1 0.380
2 0.380
3 -20
4 0.420
5 0.400
6 -20
kda500 power supply {not working properly}
right to left
4 pin
brown 8.06
black 7.93
white -0.11
gray -0.10
5 pin
green 30.16
blue 3.29
green 2.58
red/white 3.01
red 1.11
3 pin
yellow -.759 <—— this should be -13-15VDC
light blue -0.024
yellow 13.78
3 pin
black 165
brown -166
red -165
Kda1000 operating normally
4 pin
brown 8.52
black 8.92
white -0.003
gray - 0.003
5 pin
green 32
blue 3.33
green 2.6
red/white 3.05
red 1.1
3 pin
yellow -13.7
light blue 0
yellow 13.8
3 pin
black 157.5
brown -157.8
red -157.8
55bz<—- need help identifying what this is as it is not giving me proper voltages
these are the measurements from the working power supply on the 55BZ smd component
1 -18.2
2 -18.2
3 -5.83
4 -18.71
5 -18.71
6 -18.71
The measurements from the non working power supply 55BZ chip
1 0.380
2 0.380
3 -20
4 0.420
5 0.400
6 -20
3
Microcontrollers / Re: Divide clock by 3 on a ATF16V8B
« Last post by RoGeorge on Today at 11:47:36 am »Does it has to be with a PLD?
For relatively constant Fin, a divider by 3 can be implemented with a HC74 D-type flip-flop and an LC, like this:
Found this unusual dividers idea from a PDF by Charles Wenzel, where a tuned LC is inserted in a typical D-type FF divider by 2, so to make it divide with ratios other than 2.
Tried that once, to divide by 3 a 4.9152MHz TTL oscillator. It worked very well, stable and not picky to the exact LC values (as long as the LC values are not totally off).
For relatively constant Fin, a divider by 3 can be implemented with a HC74 D-type flip-flop and an LC, like this:
Found this unusual dividers idea from a PDF by Charles Wenzel, where a tuned LC is inserted in a typical D-type FF divider by 2, so to make it divide with ratios other than 2.
Tried that once, to divide by 3 a 4.9152MHz TTL oscillator. It worked very well, stable and not picky to the exact LC values (as long as the LC values are not totally off).
4
Beginners / Re: Comparator circuit seems to be oscillating (well, pulsing, really). Solutions?
« Last post by T3sl4co1l on Today at 11:45:36 am »Hi
I need your help.
I have checked the capacitors on my digital piano and got the following results in ESR levels. I used the peak ATLAS ESR70 gold.
10000 uF 25V - ESR 0.01
2200 uF 25V - ESR 0.02
470 uF 10V - ESR 0.20
100 uF 25V - ESR 0.43
47 uF 16V - ESR 0.64
10 uF 16V - ESR 1.01
1 uF 50V - ESR 1.10
I am especially suspicious about ther results for 10 micro and 1 micro F. They should be around 8 and 5 respectively. Do these results mean that I need to change the 10 micro and 1 micro D capacitors?
Thanks for your replies.
Tan
Please start a new thread; this bears no relation to the topic above.
5
Dodgy Technology / Re: 10ah 18650 cells
« Last post by Kean on Today at 11:42:43 am »I bought 48 pcs of HG2 18650 from an AliExpress seller that were specified for 3000mAh down to 2.5V.
I've only been test discharging them so far at 1A to 3.0V, and have been getting pretty consistent readings of 1800mAh.
So not great, but certainly not as bad as some reports I've seen - and for the price I paid compared to local trustworthy suppliers I am happy.
I will be assembling these into packs that go inside some 12V SLA shells for backup power application.
Some of my other purchases of 18650 cells and packs in December/January never arrived, but AE did process refunds on those.
I've only been test discharging them so far at 1A to 3.0V, and have been getting pretty consistent readings of 1800mAh.
So not great, but certainly not as bad as some reports I've seen - and for the price I paid compared to local trustworthy suppliers I am happy.
I will be assembling these into packs that go inside some 12V SLA shells for backup power application.
Some of my other purchases of 18650 cells and packs in December/January never arrived, but AE did process refunds on those.
6
Beginners / Re: Why are thermal jumpers so expensive?
« Last post by T3sl4co1l on Today at 11:41:35 am »Mind, Al2O3 isn't bad, it's just not as good as metal (or AlN or BeO, lol). That's still good enough for a lot of things.
You can get ceramic (I think more generic porcelain) heatsinks, it might not be great but it's better than air, and might be used to just take a few to tens of degrees off an IC or whatever. There were also... maybe they're still available somewhere, but someone made extruded/HIP Al2O3 heatsinks. ... Aha, here they were: https://www.ohmite.com/wc-series-heatsink/ also CA series (now discontinued?), and also Wakefield CE-OMNI-38, so I guess there is one surviving [equivalent] line across two mfgs (or maybe they're both from a common source and selling as brands, who knows).
Main thing is, plopping hunks of ceramic around a design isn't going to do much unless there's good thermal contact between everything. An SMT chip can't be very big to still be a chip, which makes AlN great for it, and the solder is good thermal contact. Al2O3 is good, but not great, and the low aspect ratio of a chip hurts more; it would have to be more cubic to do a comparable job.
Or insulator plates and such, but they have to be fairly thick for strength, which somewhat defeats the purpose. Not to mention the plates themselves might not be very smooth, and heatsinks are rarely very planar, so you still need a generous dose of grease to fill everything in.
I suppose a potting compound filled with Al2O3 sand would be pretty effective (not to mention, torture to excavate
). A lot of thermal potting compounds are basically that, or ZnO or other ceramics, and they do pretty well overall.
Tim
You can get ceramic (I think more generic porcelain) heatsinks, it might not be great but it's better than air, and might be used to just take a few to tens of degrees off an IC or whatever. There were also... maybe they're still available somewhere, but someone made extruded/HIP Al2O3 heatsinks. ... Aha, here they were: https://www.ohmite.com/wc-series-heatsink/ also CA series (now discontinued?), and also Wakefield CE-OMNI-38, so I guess there is one surviving [equivalent] line across two mfgs (or maybe they're both from a common source and selling as brands, who knows).
Main thing is, plopping hunks of ceramic around a design isn't going to do much unless there's good thermal contact between everything. An SMT chip can't be very big to still be a chip, which makes AlN great for it, and the solder is good thermal contact. Al2O3 is good, but not great, and the low aspect ratio of a chip hurts more; it would have to be more cubic to do a comparable job.
Or insulator plates and such, but they have to be fairly thick for strength, which somewhat defeats the purpose. Not to mention the plates themselves might not be very smooth, and heatsinks are rarely very planar, so you still need a generous dose of grease to fill everything in.
I suppose a potting compound filled with Al2O3 sand would be pretty effective (not to mention, torture to excavate
). A lot of thermal potting compounds are basically that, or ZnO or other ceramics, and they do pretty well overall.Tim
7
Power/Renewable Energy/EV's / Re: Why are all Vicor PI3 modules suddenly out of stock or obsolete?
« Last post by Faringdon on Today at 11:34:34 am »You have contacted your local Apps Guy from VicorPower?.
I find with Vicor you need to do that.
I find with Vicor you need to do that.
8
Microcontrollers / Re: Has anyone used ASAN & MSAN, and relevance to embedded arm32
« Last post by peter-h on Today at 11:33:42 am »Yes; those help with a) using the FreeRTOS internal heap (which I don't use) and b) overrun of the task stack due to e.g. some function which has big local variables.
The problem with using those checks is that they only tell you if the thing has blown up. One needs a separate tool to check if there is enough margin. I got a graphical tool developed on freelancer.com which shows the 64k RTOS stack area and it shows the unused stack space etc. Anyway that's a bit off topic
The problem with using those checks is that they only tell you if the thing has blown up. One needs a separate tool to check if there is enough margin. I got a graphical tool developed on freelancer.com which shows the 64k RTOS stack area and it shows the unused stack space etc. Anyway that's a bit off topic
9
FPGA / Re: Analog video output with FPGA ?
« Last post by langwadt on Today at 11:26:24 am »If you want 8 bits per channel, look for the cheapest RGB video DACs and be done with it. I know it's overkill, at these thing can run at +200Mhz, but it's easy and regulated outputs, with 75ohm cable driver built in with static immune outputs.
Try this guy:
ADV7125xxxxxx are still available at $7 to $9 USD a piece. (search for alternate suffix as the 330MHz version I listed may be overkill)
ADV7123xxxxx are available at $5.37 USD, but you will need to buy 10 of them. These are the cheapest if you go to ~25 pieces at they drop to $4.40 USD.
you can also get a clone of the ADV7123, for ~$2
https://www.lcsc.com/product-detail/Digital-To-Analog-Converters-DACs_HTCSEMI-HT7123ARQZ_C2886392.html
10
Projects, Designs, and Technical Stuff / Re: Accurate sine wave in terms of amplitude
« Last post by sw_guy on Today at 11:19:16 am »>What is the target distortion ?
I do not know yet.
One option is that: do not care. I can measure what the amplitude is and then do the math one way or another.
I do not know yet.
One option is that: do not care. I can measure what the amplitude is and then do the math one way or another.