I’d just make new ‘PCBs’ in KiCad, with the dimensions from Pete’s drawings and then order Aluminium PCBs (JLCPCB has those e.g.). From KiCad you’ll get Gerbers ready to send…
P.s. Normal 1.6mm PCB material ok and probably less expensive, other thickness possible too.
P.s. Normal 1.6mm PCB material ok and probably less expensive, other thickness possible too.
After a bit of head scratching, I found the EasyEDA tool from JLCPCB could import Pete's DXF. It lost the text, but the panel dimensions and cutouts were OK, so I added the text manually. Then am going to try ordering aluminum PCBs, white with black top silk mask for the text.
Has anyone successfully used a DK201 panel meter instead of the unobtainium original?
The pinout is different, but I'm more concerned whether the functionality is the same.
In the original MDMV000, the annunciators (inputs for e.g. decimal point, m, V etc) are driven by signal BP and BPN, short for 'backplane' and 'not backplane'. In the documentation for that display it says 'connect the annunciators to BPN for it to appear' i.e. turn on, and annunciators not in use connect to BP i.e turn off.
The soundcard circuit has the used annunciators driven by XOR gates, one input of which is BPN. So it would appear BPN is outputting a TTL level, is it some kind of strobe? Why is it necessary to use an xor gate driven by BPN rather than the switch directly?
The DK201 appears to have something similar, a 'BP' (backplane) and 'XBP' pin (referred to as annunciator and decimal point driver in the datasheet). Are these the same?
Having wired the display onto a breadboard, applied 5V VDD and connected s low voltage source to the input I can get the DK201 to read e.g. 1600 for 0.16v input which is correct, if I check the voltage on the XBP pin its about 60mV dc (no sign of a strobe signal). So very curious as to what the backplane signals are and how they work.
-Keith
The pinout is different, but I'm more concerned whether the functionality is the same.
In the original MDMV000, the annunciators (inputs for e.g. decimal point, m, V etc) are driven by signal BP and BPN, short for 'backplane' and 'not backplane'. In the documentation for that display it says 'connect the annunciators to BPN for it to appear' i.e. turn on, and annunciators not in use connect to BP i.e turn off.
The soundcard circuit has the used annunciators driven by XOR gates, one input of which is BPN. So it would appear BPN is outputting a TTL level, is it some kind of strobe? Why is it necessary to use an xor gate driven by BPN rather than the switch directly?
The DK201 appears to have something similar, a 'BP' (backplane) and 'XBP' pin (referred to as annunciator and decimal point driver in the datasheet). Are these the same?
Having wired the display onto a breadboard, applied 5V VDD and connected s low voltage source to the input I can get the DK201 to read e.g. 1600 for 0.16v input which is correct, if I check the voltage on the XBP pin its about 60mV dc (no sign of a strobe signal). So very curious as to what the backplane signals are and how they work.
-Keith
I used the one attached, supplied by Mouser. It doesn’t fit any panel and needs to be hand wired to the original PCB but works as expected incl. decimal point without the need to change the original circuit.
P.s.
In my new design I replaced the whole thing by a combination of LTC1966 (true RMS converter), LT1494 (buffer) and 1706 (0-200mV, single input digital panel, supplied by Aliexpress). This won’t give you a decimal point which I ‘faked’ with four LEDs…
P.s.
In my new design I replaced the whole thing by a combination of LTC1966 (true RMS converter), LT1494 (buffer) and 1706 (0-200mV, single input digital panel, supplied by Aliexpress). This won’t give you a decimal point which I ‘faked’ with four LEDs…
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Interested. I know I am being very lazy, but do you have a Mouser project for the new parts?
Unfortunately I don’t have one, since I ordered parts for three projects at the time…
But you can go with Pete’s BOM and strip parts for the SC output. The LTC1966 are modules from Aliexpress ($10 each) and the 1706 is a single input Panel (YB5135D Digital Voltmeter DC200mV) from Ali ($10 each) as well. The LT 1494 is a dip. I kept the other parts. Look at my schematic above nothing special…
The dual voltage inverter is a CUI Inc PUZ3-D5-D15-D (4.5-9V to ± 15V).
PM me and I’ll send you my KiCad files then you can run a BOM and/or make mods…
But you can go with Pete’s BOM and strip parts for the SC output. The LTC1966 are modules from Aliexpress ($10 each) and the 1706 is a single input Panel (YB5135D Digital Voltmeter DC200mV) from Ali ($10 each) as well. The LT 1494 is a dip. I kept the other parts. Look at my schematic above nothing special…
The dual voltage inverter is a CUI Inc PUZ3-D5-D15-D (4.5-9V to ± 15V).
PM me and I’ll send you my KiCad files then you can run a BOM and/or make mods…
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Can anyone say how to set the stops for the range switch to get the 4 positions set correctly? Thanks.
You need to unscrew the big nut and rotate the lock ring into the right position. The datasheet you get from mouser or DigiKey has a tutorial with pics.
Thanks, but the switch I have doesn't have a lock ring. It has two tiny, needle-like pins which can be put into small holes in the front of the switch. But although it's easy enough to work out how far apart they must be to get 4 positions out of the maximum, getting them so the range switch goes from the lowest to highest range isn't obvious.
RTFM, it’s all in there…
Or try and error, lol
P.s.
If someone is considering replacing the AD536 with modern LTC1966, you can get them from Ali, but be aware there are quite a few faulty modules sold. These modules won’t work out of the box because the PCB has an error since pin one of the LTC is not connected to GND. After running a small bridge these modules will also work flawlessly. Don’t skip the LT1494 buffer it’s required for smooth output (see application notes).
Or try and error, lol
P.s.
If someone is considering replacing the AD536 with modern LTC1966, you can get them from Ali, but be aware there are quite a few faulty modules sold. These modules won’t work out of the box because the PCB has an error since pin one of the LTC is not connected to GND. After running a small bridge these modules will also work flawlessly. Don’t skip the LT1494 buffer it’s required for smooth output (see application notes).
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Yes, it's called a QA403 audio analyzer, though you'll have to pony up $599... It's ready to go right out of the box.
QA403 - pretty much out of the box - you probably need some cables though, it takes BNC... I have one and its excellent for the money IMO, support is good.
Hi, thanks, I know this device by an internet forum.
But expensive and I first want to try measurements with cheaper equipment before I spend this money.
But expensive and I first want to try measurements with cheaper equipment before I spend this money.
cfortner -
Very inexpensive compared to anything in the Audio Precision lineup. If you go the sound card route, you will need some sort of interface in between so you don't blow up the input of the sound card with, say, a power amplifier output signal. You can build the Pete Millett box, but you will need some construction skills to make it look (and act) decent.
Very inexpensive compared to anything in the Audio Precision lineup. If you go the sound card route, you will need some sort of interface in between so you don't blow up the input of the sound card with, say, a power amplifier output signal. You can build the Pete Millett box, but you will need some construction skills to make it look (and act) decent.
I can get RCA-BNC adapters that will likely work well with the QA403. Some BNC -to easy- hook cables would probably come in handy, too. I've also heard that it's a bit power hungry and prefers to be run from something like a powered USB hub.
The output of a tube amp is considerably less voltage that at the gut level, as you have a step-down transformer. I'll need to check to be sure, but the QA403 may likely handle that just fine. Anyone who goes probing around in the guts of a tube amplifier with a sensitive and delicate audio analyzer is pretty much crazy from the get-go.
Cheap 100x scope probe from ebay works well if your soundcard has an unbalanced instrument input of circa 1Megohm. I use it with two metal interfaces: 1/4" to RCA, and RCA to BNC.