I changed R1 to 18R and the transformer secondary to 18V. Instead of the load resistor I used a current sink set to 10mA. This gets me 19V with 490uV ripple.
You could also use a switchmode power supply. This would be cheaper and smaller.
You could also use a switchmode power supply. This would be cheaper and smaller.
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is this the same as a voltage regulator?
I think I'd like to keep it a bit higher, around 24V, but I see what you did.
Aside from knowing they're more efficient, quieter, and smaller, I know nothing about them. I can get the one I used in this example for $8 US. Can someone suggest something similar, but Switch mode? Should I just cut open a wal-wart?
uhh pls don't cut open a wall wart, it defeats the safety aspect and even if you do succeed, you will probably end up a big mess-o-junk E.g. glue or potting compound.
13.8VDC is more than enough for any pre-amp or effects electronics, in fact most use a 9V battery that goes down to 6-7 volts. the HF PSU in my link could attach to "your box" by a plug and a jack , putting a switching power supply inside an existing commercial amp has all kinds of consequences most are negative ...let use help you re- think your whole concept! what is it? why 24Vdc?
BTW there are brand new, very good rechargeable Li-ion batteries ( 2-cells) in the same old 9V form factor in combination with using newer (low Iq ~ 2mA ) op-amps will make outstanding solutions.
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Point taken, scratch that!
Well, it's as I said in my first post. I know there are rechargeable, etc. but I have 8 basses, all active, and some have LED's in them too. I've just... HAD IT with batteries.
I prefer 18 volts to 9, and would like to use up to 24 (I'd make it switchable) because I like the extra headroom - subtlety is not in my style of playing.
Good catch! I didn't type a second 'zero'. about 80-100mA for 12 LED's
OH, check this out -
I was just digging through some old parts and found a chassis, with an AC plug, fuse, and 1/4" jacks all mounted up along with a Hammond PT442 transformer, with an empty board I can use to mount electronics!
https://www.tubesandmore.com/products/P-T442
Can we make this work, or is it just too much voltage??
I was just digging through some old parts and found a chassis, with an AC plug, fuse, and 1/4" jacks all mounted up along with a Hammond PT442 transformer, with an empty board I can use to mount electronics!
https://www.tubesandmore.com/products/P-T442
Can we make this work, or is it just too much voltage??
how do you know you don't already have headroom with 9V? I think this is arbitrary design / thinking.
I don't get it ,youre going to modify all your instruments, cables, and amplifier, just to be rid of 9V batteries? What does that do to resale / trade in value?
Consider better rechargeable batteries and/or dis-connecting LEDs, replacing op-amps etc.
I don't get it ,youre going to modify all your instruments, cables, and amplifier, just to be rid of 9V batteries? What does that do to resale / trade in value?
Consider better rechargeable batteries and/or dis-connecting LEDs, replacing op-amps etc.
Nope. It's not night and day, but there is a discernible difference. 18+V sounds better than 9V, IMO. The pickups are rated to 27V. The difference is less pronounced going from two 9V to three 9V batteries (I can't hear it without really listening, and then it's not enough of a difference.) but it's clearly audible from 9V to 18V.
No cable mod, it will be a 1/4"TRS cable. The instrument mod is simply to remove the batteries and connect the pickup hot wire to the 'ring' of the existing TRS jack. The resale value of the basses would be simply to reverse - but I'm never going to sell all but perhaps two of them. The pre-amp I use is home made, but I want this to be it's own box anyway. There isn't enough room to do it in my pre-amp.
The audio portion would just pass-through to 1/4" tip-sleeve jacks on the back.
Kinda like this,
http://www.emgpickups.com/es-18.html
except that EMG's available AC power supply sucks - it's been reviewed as REALLY noisy, buzzy, etc. Also EMG's unit is $100 for $15 worth of components - many of which I own already.
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thanks for the link, IDK guitars had stereo 1/4" jacks now.
just make a foot pedal box like in your link and install a DC power jack on the side (put a reverse diode across the pins to protect), then u can use an 'outboard' wall wart type of supply or any kind of batteries you want.
I'd def. recommend a DC output type of wall wart for lowest noise and use a LM317 mounted inside the foot pedal.
i'd use one like this "(PS) 102269 from Nebraska Surplus sales" 22VDC 140mA and design the LM317 for 18V out
needs about 3-5 VDC across input to output for best sound.
just make a foot pedal box like in your link and install a DC power jack on the side (put a reverse diode across the pins to protect), then u can use an 'outboard' wall wart type of supply or any kind of batteries you want.
I'd def. recommend a DC output type of wall wart for lowest noise and use a LM317 mounted inside the foot pedal.
i'd use one like this "(PS) 102269 from Nebraska Surplus sales" 22VDC 140mA and design the LM317 for 18V out
needs about 3-5 VDC across input to output for best sound.
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yep, it's how actives switch off the batterry power - by diconnecting the power ground from earth ground.
Well, this is exactly what EMG does with their box - and it's HORRIBLY noisy from what I've read across multiple forums. I still feel my idea of a highly filtered and regulated PS after a transformer, like one used in a pre-amp, is my best bet.
So, now I'm wondering if I can make an ultra-quiet power supply using this :
https://www.tubesandmore.com/products/P-T442
which I found all wired up with a fuse and AC mains in a chassis I already have...
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don't dismiss a properly designed LM317 and a decent wall wart, it'll compare with the best of em.
if what they did is noisy they did someting wong. (show me the details and ill add comments)
if what they did is noisy they did someting wong. (show me the details and ill add comments)
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Oh - I'm guessing they didn't use the regulator. They likely only did the wal-wart straight into the box as a 9V supply in place of the batteries.
I'll bet the LM317 alone would smooth it out considerably.
I will play with it in PSDII - although I'm still trying to learn that program... I know if the line is nice and smooth, it's good, LOL
I'll bet the LM317 alone would smooth it out considerably.
I will play with it in PSDII - although I'm still trying to learn that program... I know if the line is nice and smooth, it's good, LOL
you don't need that program for a standard full wave rectifier into a biggish cap.
rule of thumb is 2200 uF per Ampere gives 1V RMS 120Hz ripple.
Voltage regulator knocks that right down ~ 60 dB and any good op-amp has PSRR another 50-60 dB.
small EI transformer will sag the average voltage ~ 7-10% at rated current. but I don't recommend operation past 1/2 rated anyways depending on poor cooling of potted devices
rule of thumb is 2200 uF per Ampere gives 1V RMS 120Hz ripple.
Voltage regulator knocks that right down ~ 60 dB and any good op-amp has PSRR another 50-60 dB.
small EI transformer will sag the average voltage ~ 7-10% at rated current. but I don't recommend operation past 1/2 rated anyways depending on poor cooling of potted devices
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so design for 0.2A use 470 uF at the bridge, now the output of regulator is -60dB down or 1/1000 ~ or 1mV RMS at full load. The opamp knocks that down another 1/1000 or 1uV or 2.8uV p-p. design under loading ( V regulation) make sure the lowest level seen at the bulk capacitor is ~5V above the LM317 Vout. note use >10uF cap at the adjust pin and another at the output for better noise performance and dynamic stabilty.
V regulator heat sink needs to dissipate ~ 1.1 watts = 0.2A * (Vin-Vout)* (RF) where RF = regulation factor at light loads
V regulator heat sink needs to dissipate ~ 1.1 watts = 0.2A * (Vin-Vout)* (RF) where RF = regulation factor at light loads
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I appreciate your trying to help - but now you've officially gone WAY over my head, LOL!
I've designed (well, copied) very basic (but VERY quiet) power supplies using a transformer, bridge, RC voltage divider, and even one with a regulator once. but that's the length of my knowledge.
Where did the op-amp come from? Why am I using a big wal-wart for $10, when I can use a tiny transformer on the first page of this thread for $7 - (or the one I already have for free)? Why am I hauling around a wal-wart instead of just plugging my box in - and not be stuck with... a wal-wart?
I'm not criticizing, I just don't understand what you propose.
I've designed (well, copied) very basic (but VERY quiet) power supplies using a transformer, bridge, RC voltage divider, and even one with a regulator once. but that's the length of my knowledge.
Where did the op-amp come from? Why am I using a big wal-wart for $10, when I can use a tiny transformer on the first page of this thread for $7 - (or the one I already have for free)? Why am I hauling around a wal-wart instead of just plugging my box in - and not be stuck with... a wal-wart?
I'm not criticizing, I just don't understand what you propose.
1) wall warts are keeping you safe and most of all to keep from adding another earth ground into your box (can you say ground loop hums!) 3wire AC plug Vs 2 wire wall warts. besides all that stuff your free XFMR wont work very well here.
see circuit 9.3.2 here http://www.ti.com/lit/ds/symlink/lm317.pdf
that regulator design, and one of two the XFMRs in my other link above giving 22.5V DC will work very nice for 18V
op-amp IDK what are your requirements for low noise and ripple specifically? designing for lots of "headroom" is kinda too touchy feely for me.
IDK maybe you have the wrong guitar and amp? all this battery replacement stuff is old well traveled ground I'm sure.
see circuit 9.3.2 here http://www.ti.com/lit/ds/symlink/lm317.pdf
that regulator design, and one of two the XFMRs in my other link above giving 22.5V DC will work very nice for 18V
op-amp IDK what are your requirements for low noise and ripple specifically? designing for lots of "headroom" is kinda too touchy feely for me.
IDK maybe you have the wrong guitar and amp? all this battery replacement stuff is old well traveled ground I'm sure.
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I see. Safety (good) ground loops (bad). Maybe it's just my phobia as a musician for all things wal-wart. We hatses them, precious!
Pictures are good! More pictures!! So, Essentially, you're just saying run the VDC from the outboard wal-wart you suggest, into my box, where there's a board with the LM317 and resistor to bias.
No diode bridge? RC divider to further smooth ripple? The wal-wart is kept outboard to reduce the noise that comes from switching power?
Pictures are good! More pictures!! So, Essentially, you're just saying run the VDC from the outboard wal-wart you suggest, into my box, where there's a board with the LM317 and resistor to bias.
No diode bridge? RC divider to further smooth ripple? The wal-wart is kept outboard to reduce the noise that comes from switching power?
remember batteries are 2 wire devices if you want to use 120 AC to plug in your box you MUST add a third wire. I'm not going to help you add junk inside your amp sorry
yes DC wall warts keep AC switching away from sensitive instruments and cables, I think you need better guitar electronics for good battery life jeeze were talking a 1 or 2 dollar item. gotta gig? just put a new one in, done. go to the dollar stores I see they two 9V HD batteries for a buck.
yes DC wall warts keep AC switching away from sensitive instruments and cables, I think you need better guitar electronics for good battery life jeeze were talking a 1 or 2 dollar item. gotta gig? just put a new one in, done. go to the dollar stores I see they two 9V HD batteries for a buck.
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Thank you, Captain Safety.
I'm quite capable of building and working with electronics projects, including high voltage guitar amplifiers, and have done so for years. Thus far I've somehow miraculously survived, with a good degree of safety even. Somehow, I have done so without profound yet stupidly obvious tips such as these.
Incidentally, and this must come as a *shock* to you, I am already HERE, asking for HELP.
I was asking about components and design with which I am not yet familiar.
How about contributing something, instead of... not?
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