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Post by chinook9 on May 21, 2014 16:51:51 GMT
Frans has sent me a few PCBs and over the next few weeks I will embark on an attempt to build T50RP and LCD-3 filters. I expect I will be asking for some help in this thread.
I have read the first 12 pages of the filter guide but I am not a technician and will have to learn more electronics to complete either of these filters. I studied electronics in 1964 and never worked as a technician so that gives you a clue. I have a soldering station and am capable as far as soldering/unsoldering components on a PCB.
First off, I would like to settle on a power supply option. I would like a recommendation for the easiest option to build and to understand. If anyone has a picture, that might be all I need, however, I would also like to know the part number of the DC to DC converter used. Before today I had never heard of these.
For power, I could use 9 volt batteries or I could obtain any type of walwart with no trouble or expense.
I appreciate any advise/help.
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solderdude
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Post by solderdude on May 21, 2014 17:00:31 GMT
9V batteries could be O.K. for testing but aren't suited for the long run as they will be depleted quickly unless you use TS912 opamps.
Power options depends on the power supplies you might have available.
If you have 5V, 12V, 24 V or even 48V power supplies on hand.
These must be regulated or switch mode and would have to be able to deliver 3W at least.
Most people have 1 or 2 wallwarts somewhere they don't use.
If you happen to have a +/- 12V or +/- 15V power supply around doing nothing this is a good time to use it.
If you have a 18V to 30V regulated single power supply at hand (preferably with a trafo, not an SMPS) then that could be put to use as well.
So the power supply options will depend on what you have available, it is also why I catered for all these different options, to keep it flexible.
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Post by chinook9 on May 21, 2014 18:08:25 GMT
Frans I will look around locally and see whats available in walwarts. There are many of them available at local used goods stores.
Also, how about just powering it from the 13.8 volt 2.5 amp (3 amp surge) regulated power supply I use to power my Musical Fidelity V-DAC?
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Post by solderdude on May 21, 2014 18:53:13 GMT
That is possible.
The DC input voltage would have to be lowered a bit which is very easy to do with 2 or 3 diodes.
You would be needing a 12V input 2W DCDC converter
There are several options in that case IH1212S, TMH1212D, NMH1212S, RD-1212D
or you can use the +/-15V versions IH1215S, TMH1215D, NMH1215S, RD-1215D
These will (galvanically isolated) convert 12V to +/-12V or +/-15V which would depend on the choice of opamp you would like to use.
Any of the following op-amps can be used (and has been tested)
NE5532, OP275, LM6172, OPA2132/2134, LT1361, NJM4556, LM4562
The NE5532, OP275, OPA2132, OPA2134, LM4562 are all good candidates and can all run on +/-15V
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Post by chinook9 on May 21, 2014 19:42:46 GMT
Thank you for the information Frans. I just picked up a few walwarts ($1 each) (12V 1.5Amp, 12V 1Amp, 24V 0.84 amp, 32V 0.844 amps) which, I expect may be easier to use, and should do the job. I'll do some more reading on these.
I may already have some of the opamps. I'll have to get out my magnifying glass and check them out.
Good night!
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Post by chinook9 on May 26, 2014 14:41:42 GMT
Frans, am I correct in assuming that the filter previously referred in this thread by micmacmo as p35 is now p37?
Also, I checked the output of the wallwarts and the 12V 1A actually measured over 17 volts. I'll go with the 12V 1.5A one. It measured 12 volts. The others also measured as indicated.
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solderdude
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Post by solderdude on May 26, 2014 14:56:56 GMT
Yes in latest manual it is page 37.
The filter on page 36 has the ability to tune the 3kHz dip and treble extension separately.
The filter on page 37 has a fixed increase in mids and treble and the notch section removes (filters) the 9kHz peak.
the 17V version appears to be a non-regulated type (simple transformer + rectifier.
The ones that measure an exact voltage are SMPS type.
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Post by chinook9 on May 26, 2014 15:14:24 GMT
Great!, thank you Frans. I'll check out the page 36 version, it sounds more up my alley.
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Post by solderdude on May 26, 2014 15:29:39 GMT
It has slightly higher noise level though as it has 2 notch sections.
I use the page 36 version on my own T50RP and a 'page 37 alike' version on the Kameleon.
If you have the volume control after the filter that should not be a problem though.
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Post by chinook9 on May 26, 2014 15:31:19 GMT
Thanks. Have a good evening.
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Post by chinook9 on Jul 3, 2014 21:17:27 GMT
Well folks, I have received the parts I ordered from Mouser and Parts Express and I have my first question. I will be using a 12 volt wall wart as a power supply and so I ordered a Murata NMH1212DC DC/DC converter. This one: www.mouser.com/ProductDetail/Murata-Power-Solutions/NMH1212DC/?qs=e/4tzKJ%252blEZJOXiaO5NvaA==I expect you already know that the pin configuration is quite different than that needed. Is there a specification I need to look for to confirm the correct pin configuration? |
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Post by solderdude on Jul 3, 2014 21:28:43 GMT
You needed the NMH1212SC but you can also use this one but have to glue it on the PCB and wire it to the PCB On page 5 of 6 (not 7 of 9  ) of the file below you can see which pins on the 14 DIP should go where when a 7 SIP would have been used. www.mouser.com/ds/2/281/kdc_nmh-55655.pdfNC means Not Connected |
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Post by chinook9 on Jul 3, 2014 22:11:57 GMT
You needed the NMH1212SC but you can also use this one but have to glue it on the PCB and wire it to the PCB On page 5 of 6 (not 7 of 9 ) of the file below you can see which pins on the 14 DIP should go where when a 7 SIP would have been used. www.mouser.com/ds/2/281/kdc_nmh-55655.pdfNC means Not Connected Thank you Frans. I will order an NMH1212SC so that it fits better. I only ordered 2 of the trimmer resistors, instead of 4, so I need to place another order anyway. The 1uF capacitors I received (C102,C202) will fit more easily in the outer holes. I'd like to confirm that's OK? If not, I can make them work using the narrow spacing. |
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Post by solderdude on Jul 4, 2014 5:00:06 GMT
C102,202 can be either 1mil or 2mil.
If you have one wider than that (say 3mil) it is no problem to bend the pins and use the outer holes.
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Post by chinook9 on Jul 4, 2014 14:33:14 GMT
Thank you Frans. Can you point me at an isolated power connector (any common size will do) that will fit in the aluminum Hammond enclosure? I have been unable to find an isolated jack that will fit into a drilled hole. Jeremy provided me a BOM that included the following www.mouser.com/ProductDetail/Switchcraft/PC722A/?qs=MW%252b0w7tSdpnJ65YeXKyakg==but it does not appear to be isolated and I don't know how he was using it. |
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) of the file below you can see which pins on the 14 DIP should go where when a 7 SIP would have been used.