I am looking for the most practical way to obtain +15v/-15v off a standard +9V pedal supply.
I understand there are special DC-DC converters such as the Murata NMA0515SC which can take 5V and output 15v/-15v. http://www.mouser.com/ProductDetail/Murata/NMA0515SC/?qs=%2fha2pyFaduhFiAPVWrTrFQM2YxeR6Wl2ZuHmK8xFWK4%3d (http://www.mouser.com/ProductDetail/Murata/NMA0515SC/?qs=%2fha2pyFaduhFiAPVWrTrFQM2YxeR6Wl2ZuHmK8xFWK4%3d)
The problem with these is that they are expensive, and require a 5VDC input.
Is there any issues with say using a standard TC1044SCPA to boost the 9V voltage to +18v, regulate the output with a 15v regulator, and then use another TC1044SCPA to invert this result to +15/-15v?
Current use is not of upmost importance, as my intentions are not to use a 9V battery of course. I may be splitting hairs here but the Murata solution looks pretty easy...could be about the same cost (and area cost) as using several TC1044.
Thanks in advance. -Ben
Check out figure 24 of the LT1054 spec sheet. You can do it that way with one charge pump and two regulators.
Current use with respects to the draw on the battery is not the concern. The current draw of the circuit on the pump is where you may run into trouble. If your circuit is drawing more current than the charge pump can deliver, you will see degraded performance in the form of distortion or even circuit failure.
Do you know how many mA the circuit(s) will pull? My golden rule (with the LT1054) is 50mA. If the circuit pulls more than 50mA then I need to figure out another way. Of course, I have "heard" that the LT1054 can be used up to 100mA but, I have not tried it. Also, that was purely as a doubler. You are looking for a positive doubler AND a negative doubler. Might need some figuring out and experimentation.
Awesome guys. Looks like this is the one here:
Am I correct that the TC1044SCPA is pretty much the same and can be substituted here?
(https://dl.dropboxusercontent.com/u/73135424/SDD3000/LT1054.png)
Thanks for explaining this. I'll assuredly will have to experiment with it and see what the resulting current draw is.
Quote from: Govmnt_Lacky on January 02, 2014, 04:13:57 PM
Current use with respects to the draw on the battery is not the concern. The current draw of the circuit on the pump is where you may run into trouble. If your circuit is drawing more current than the charge pump can deliver, you will see degraded performance in the form of distortion or even circuit failure.
Do you know how many mA the circuit(s) will pull? My golden rule (with the LT1054) is 50mA. If the circuit pulls more than 50mA then I need to figure out another way. Of course, I have "heard" that the LT1054 can be used up to 100mA but, I have not tried it. Also, that was purely as a doubler. You are looking for a positive doubler AND a negative doubler. Might need some figuring out and experimentation.
Output current is 100mA for the regular 1054 and 125mA for the 1054L (but that can only take 7V in). It's in the datasheet, and it also scales with the supply current from the power source up to 120mA. They're not going to overestimate the current delivered because that's a really good way to piss people off (just like you never see a maximum voltage rating underestimated), and you can probably squeeze a little more out of it. Lots of people have used the 1054 in univibe clones, which easily draw far more than 50mA, but there's no reason to rely on hearsay when the datasheet gives you maximum ratings.
The main drawback to supplying as much voltage as possible is that it increases the voltage loss. You lose about a half volt extra of voltage when drawing more current than you do when drawing very little.
Quote from: rullywowr on January 02, 2014, 04:22:21 PM
Am I correct that the TC1044SCPA is pretty much the same and can be substituted here?
Yes and no. Understand that the TC1044/Max1044 are different than the LT1054. Largely it's about current draw and voltage input. Again, the question is - how much voltage are you feeding and how much voltage are you wanting out?
Also, you can do it with some voltage dividing, instead of using regulators on the end. For instance, if you need +/-15V, you can take your 9V in, divide it to 7.5V, feed it into the Charge Pump, then you should have +/-15V. Just an alternative method over using the regulators, but that's just a thought, you should do the research as to which method is safer.
Jacob
Quote from: rullywowr on January 02, 2014, 04:22:21 PM
Awesome guys. Looks like this is the one here:
Am I correct that the TC1044SCPA is pretty much the same and can be substituted here?
(https://dl.dropboxusercontent.com/u/73135424/SDD3000/LT1054.png)
Thanks for explaining this. I'll assuredly will have to experiment with it and see what the resulting current draw is.
Yes that will work, and depending on what you're powering, 2 x 15V zeners could be used as shunt regulators, this was fine for several vintage EHX effects so...
One other point to using a different charge pump is the boost pin. The LT1054 doesn't need the boost pin (or have one for that matter), but if you use the TC1044SCPA, then you'll need to mod the schematic to connect the boost pin.
Thanks again. The documentation on the TC1044S is pretty weak. It looks like connecting the boost pin to V+ does raise the clock frequency out of the audible range (which should eliminate whine). It also looks like enabling the boost pin does slightly reduce efficiency until about 20mA as compared to not enabling it.
Quote from: rullywowr on January 02, 2014, 05:11:03 PM
Thanks again. The documentation on the TC1044S is pretty weak. It looks like connecting the boost pin to V+ does raise the clock frequency out of the audible range (which should eliminate whine). It also looks like enabling the boost pin does slightly reduce efficiency until about 20mA as compared to not enabling it.
Yep, that's pretty much the trade offs. I've found the TC1044S to be unusable without the boost connected though. Actually, I've had several of them that had the whine audible even when they were used with the boost in place. There is a TC7660H that works better and has a much higher clock to begin with for use in lower current settings. But, I still think the LT1054 is a better part. I would really consider it in this case where you are going to power two rails with the charge pump.
I agree, Rob. The LT1054 seems much more robust, especially concerning the output current. The TC1044 has a supply current (with boost) of about 350uA versus the LT1054 can do 4-5 mA.
@ Jacob...that is a pretty nifty idea about the voltage divider then boost/inversion.
Quote from: jkokura on January 02, 2014, 04:41:51 PM
Also, you can do it with some voltage dividing, instead of using regulators on the end. For instance, if you need +/-15V, you can take your 9V in, divide it to 7.5V, feed it into the Charge Pump, then you should have +/-15V. Just an alternative method over using the regulators, but that's just a thought, you should do the research as to which method is safer.
Dont forget that you are going to get a slight voltage drop when using it as a positive doubler (and possibly when doubling the negative voltage)
I know that when I use the LT1054 as a doubler and feed it with a 1Spot. I usually only get ~17V out and some change. Never get the full 18VDC.
Food for thought ;)
Quote from: Govmnt_Lacky on January 02, 2014, 05:38:57 PM
Quote from: jkokura on January 02, 2014, 04:41:51 PM
Also, you can do it with some voltage dividing, instead of using regulators on the end. For instance, if you need +/-15V, you can take your 9V in, divide it to 7.5V, feed it into the Charge Pump, then you should have +/-15V. Just an alternative method over using the regulators, but that's just a thought, you should do the research as to which method is safer.
Dont forget that you are going to get a slight voltage drop when using it as a positive doubler (and possibly when doubling the negative voltage)
I know that when I use the LT1054 as a doubler and feed it with a 1Spot. I usually only get ~17V out and some change. Never get the full 18VDC.
Food for thought ;)
Thanks Gov't. The goal is to get a stable +15/-15v supply so it's oK if it doesn't hit 18 exactly, it just has to be enough for the regulators to work and shave off what is needed for +/-15V. I am leaning towards LT1054 with seperate TO92 regulators at the moment.
Personally, I'd probably go with the Murata. Fewer parts, less complicated and smaller footprint.
It probably adds about $3-4 to the cost over the 1054 solution, but that'd be worth it to me for the other benefits.
How important do you feel the 220h inductors are? I've seen both with and without...
I think it's fine without 'em but I'm not an expert on that.
Here's a snip I like from the AION Korg preamp project:
(http://cl.ly/image/3E0k0G0Q0i3t/snippit.jpg)
Quote from: jubal81 on January 02, 2014, 08:02:57 PM
I think it's fine without 'em but I'm not an expert on that.
Here's a snip I like from the AION Korg preamp project:
(http://cl.ly/image/3E0k0G0Q0i3t/snippit.jpg)
wow, that's all that's involved?
How big is the converter itself? About the size of a chip? I'm rethinking a certain 15V project now ...
It's small. Like sip7 but only uses 5 pins. 6mm x 19mm (I just drew a DipTrace footprint so it's on the top of my head)
That method seems much more efficient. What's the link for the Murata's price and datasheet?
Jacob
Quote from: jkokura on January 02, 2014, 09:35:49 PM
That method seems much more efficient. What's the link for the Murata's price and datasheet?
Jacob
I've seen this device used in other circuits, both DIY and commercial....a little pricey but is a slick trick.
http://www.mouser.com/ProductDetail/Murata/NMA0515SC/?qs=%2fha2pyFaduhFiAPVWrTrFQM2YxeR6Wl2ZuHmK8xFWK4%3d (http://www.mouser.com/ProductDetail/Murata/NMA0515SC/?qs=%2fha2pyFaduhFiAPVWrTrFQM2YxeR6Wl2ZuHmK8xFWK4%3d)
Depending on how much current you need, check out the RECOM parts as well (RB-0515D). I think they are cheaper at mouser, around $5.50(US).
I've been playing with them and they are good. The only problem I've had with going this way is that the linear regulator is pretty inefficient, and since the circuit I was working on draws more current at 5V than it does at the effect voltage, the wasted current was too high. So, I tried it with a buck converter to drop the 9V to 5V and then go up from there using the RECOM part. I ended up with the dreaded clock clash. I think if you were using less current and could afford the loses of using the linear 5V regulator that this is a better path than the charge pump. The RECOM parts are small and self contained and isolated. When I use them with a 5V input supply, they provide really clean power.
Yeah, at $10 I'm not sure about it as much.
Jacob
Quote from: RobA on January 02, 2014, 10:10:02 PM
Depending on how much current you need, check out the RECOM parts as well (RB-0515D). I think they are cheaper at mouser, around $5.50(US).
I've been playing with them and they are good. The only problem I've had with going this way is that the linear regulator is pretty inefficient, and since the circuit I was working on draws more current at 5V than it does at the effect voltage, the wasted current was too high. So, I tried it with a buck converter to drop the 9V to 5V and then go up from there using the RECOM part. I ended up with the dreaded clock clash. I think if you were using less current and could afford the loses of using the linear 5V regulator that this is a better path than the charge pump. The RECOM parts are small and self contained and isolated. When I use them with a 5V input supply, they provide really clean power.
Rob, thanks for sharing this. At 1/2 price it does look promising..and has the same pinout as the Murata piece. 8)
This all seems like a lot of trouble and power dissipation to go to when you're not going to actually use a battery anyway. How important is it to start with 9v? What about just setting up a +-15v source along with the 9v? I don't know which option would be better even for my purposes, but they seem pretty close in terms of return on effort.
Quote from: derevaun on January 02, 2014, 11:08:35 PM
This all seems like a lot of trouble and power dissipation to go to when you're not going to actually use a battery anyway. How important is it to start with 9v? What about just setting up a +-15v source along with the 9v? I don't know which option would be better even for my purposes, but they seem pretty close in terms of return on effort.
It's really for those circuits which were designed for it. Many preamps and the like use this scheme. The added voltage swing creates a lot more headroom. These of course are not going to be powered off a 9v battery but rather a power supply when incorporating into a pedal format.
Right, so it seems like making a dedicated bipolar supply, back at the AC adapter stage, could be a good idea, rather than doing all the conversion in the box with the high impedance audio signals. But I can see how it would be a barrier to selling/building for others, etc.
Quote from: derevaun on January 03, 2014, 02:22:17 AM
Right, so it seems like making a dedicated bipolar supply, back at the AC adapter stage, could be a good idea, rather than doing all the conversion in the box with the high impedance audio signals. But I can see how it would be a barrier to selling/building for others, etc.
Exactly. Dedicated wall warts are a pain to deal with, ensure they are the correct one, keep with the pedal etc.
An LM317 set to 7.5V and a Bipolar TC1044 Doubler?
A little late to the discussion, but I wanted to add my perspective from doing the SDD Preamp board that was referenced earlier. I didn't do the math on the current draw, so I initially tried to use a 78L05 regulator (TO-92). It got very, very hot. And the SDD preamp circuit is just two op amps, so the base current draw at 9 volts is not a lot more than an overdrive. Anyway, I ended up using a full-size 7805 instead and it worked out great - but the lesson was, don't underestimate the multiplicative effects on current draw when going to 15V bipolar if you're accustomed to working within 9V single rail supplies.
Quote from: aion on May 09, 2014, 05:19:37 PM
A little late to the discussion, but I wanted to add my perspective from doing the SDD Preamp board that was referenced earlier. I didn't do the math on the current draw, so I initially tried to use a 78L05 regulator (TO-92). It got very, very hot. And the SDD preamp circuit is just two op amps, so the base current draw at 9 volts is not a lot more than an overdrive. Anyway, I ended up using a full-size 7805 instead and it worked out great - but the lesson was, don't underestimate the multiplicative effects on current draw when going to 15V bipolar if you're accustomed to working within 9V single rail supplies.
That's sound information, thanks. In your experience, you feel the inductors aren't required with the Murata? Just wondering what would be the worst case scenario of not using them, or if there are any drawbacks?
I don't remember exactly how I came amount using that particular schematic, but I think I adapted it from a synth project of some sort. I didn't ever try it with the inductors. It's been field-tested for awhile now and I haven't had any negative reports back, so I guess that's a good case against them?