Does anyone has a schematic of a Class D/PWM amp with these features:
-DC12V battery operated.
-Using opamp,Cmos logic gates,normal medium power transistors...
-Circuit simple enough.
????????????????????
-DC12V battery operated.
-Using opamp,Cmos logic gates,normal medium power transistors...
-Circuit simple enough.
????????????????????
Seems You want to have inconsistent requirements.😉
ps: i'd done something once, check this out on the my w.page.😎
ps: i'd done something once, check this out on the my w.page.😎
Here's one...
my class D amp
...very simple, BCA full bridge (good for single-sided 12V operation). Instead of the Opamp triangle wave generator, I recommend using an integrated function generator (like the XP2206), which is simpler and gives much better waveforms. Instead of two inductors, it's probably better to wind your own, center-tapped inductor, preferrably on an air-gapped core.
Don't expect too much regarding audio quality - it doesn't have any feedback. But hey, it's simple! and it successfully drove my 150W 12" subwoofer for quite a long time, until I damaged it by fiddling around with it...
If you're after HiFi audio, you are probably better off with a UcD design. There is a thread here
Development for a Reference Class D starting point
(it's worth reading the whole thing, though the link skips to the matured schematics)
On the topic: has anyone a schematic of how to build the simplest self-oscillating amplifier ever? Most UcD designs I've seen up to now use lots of discrete components - I guess the component count can be reduced by using integrated circuits. It doesn't have to be great sound quality - I just think it might be great for people who just want to play around with class D. It should be possible to build a self-oscillating amp with nothing more than a few opamps/comparators, a MOSFET driver, 2 MOSFETs and the filter.
my class D amp
...very simple, BCA full bridge (good for single-sided 12V operation). Instead of the Opamp triangle wave generator, I recommend using an integrated function generator (like the XP2206), which is simpler and gives much better waveforms. Instead of two inductors, it's probably better to wind your own, center-tapped inductor, preferrably on an air-gapped core.
Don't expect too much regarding audio quality - it doesn't have any feedback. But hey, it's simple! and it successfully drove my 150W 12" subwoofer for quite a long time, until I damaged it by fiddling around with it...
If you're after HiFi audio, you are probably better off with a UcD design. There is a thread here
Development for a Reference Class D starting point
(it's worth reading the whole thing, though the link skips to the matured schematics)
On the topic: has anyone a schematic of how to build the simplest self-oscillating amplifier ever? Most UcD designs I've seen up to now use lots of discrete components - I guess the component count can be reduced by using integrated circuits. It doesn't have to be great sound quality - I just think it might be great for people who just want to play around with class D. It should be possible to build a self-oscillating amp with nothing more than a few opamps/comparators, a MOSFET driver, 2 MOSFETs and the filter.
you can make a self-oscillating one with a single 555 timer
as schmitt trigger.
40106 plus transistors are also OK.
for any of them,remember to connect clamping shotekky diode at the output of switching stage.
as schmitt trigger.
40106 plus transistors are also OK.
for any of them,remember to connect clamping shotekky diode at the output of switching stage.
Leolabs said:
What about SODA, or similar?
Comparator+driver+FETs+post-filter feedback, may be very simple.
Regards, Timo
Comparator+driver+FETs+post-filter feedback, may be very simple.
Regards, Timo
edit time expired...
Here is the design, I used for "my" fast heater control. The FET driver is a HIP2101 instead of the EF pair.
Regards, Timo
Here is the design, I used for "my" fast heater control. The FET driver is a HIP2101 instead of the EF pair.
Regards, Timo
Class D Plans
There are some Class D DIY projects at www.schematicsforfree.mattsoft.net in the Audio\circuits section. Some are partial schematics but there are several complete construction projects as well.
There are some Class D DIY projects at www.schematicsforfree.mattsoft.net in the Audio\circuits section. Some are partial schematics but there are several complete construction projects as well.
sfx,
I'm thinking about building your class D amp. (just had to check if ir2112 is available here locally.)
I already have the plans to upgrade the mosfets to higher current ones and run it off a 50V car SMPS or would it be possible to run that at 50V without mods? also adding some input stage to add feedback. it will be driving 4 ohm subwoofers. at 50V I could be getting about 300W RMS per channel with those. 🙂
I'm thinking about building your class D amp. (just had to check if ir2112 is available here locally.)
I already have the plans to upgrade the mosfets to higher current ones and run it off a 50V car SMPS or would it be possible to run that at 50V without mods? also adding some input stage to add feedback. it will be driving 4 ohm subwoofers. at 50V I could be getting about 300W RMS per channel with those. 🙂
(Slightly OT)
I hope for Jan-Peter's sake that nobody starts to reverse-engineer the UcD's...
Although eventually there will be UcDclones, or UcloneD's (you-clone-these, LOL)
Nah, The original Hypex modules are at a very very good price, can't wait for free time to complete my amp.
Y
I hope for Jan-Peter's sake that nobody starts to reverse-engineer the UcD's...
Although eventually there will be UcDclones, or UcloneD's (you-clone-these, LOL)
Nah, The original Hypex modules are at a very very good price, can't wait for free time to complete my amp.
Y
Hi Yves,
I agree, the Hypex-modules are extremely good value for your money. Would be hard to diy-build any kind of discrete amplifier for less... but, still, buying a module, be it excellent, doesn't replace the act of creating your own, and the satisfaction when you get it to work 😉
Although, I have to admit, it's quite motivating to get an amp module, hack the power supply and a case in a few hours, and finish the whole project within a day 🙂 just did this with an STK086 chip amp for my subwoofer, because I didn't have time, and missed my low frequency response, after I burnt my class D amp:
clicky
djQUAN,
I think I already wrote to replace the triangle generator opamps with a function generator. I think it's also much better to replace the 2 filter coils in series per half-bridge with only one center-tapped coil. This way, the energy stored in the magnetic field can flow through the speaker during an asymmetric phase, and doesn't have to go through the diodes. Not sure though how the linearity will be. I can't try, unfortunately I damaged mine beyond repair... One day I'll make a new one.
When you choose MOSFETs, try to get some fast ones with short switching times, that still have reasonably low Rds_on. There seems to be a trade-off, but there are a few really fast high-power ones.
Cheers,
Felix
I agree, the Hypex-modules are extremely good value for your money. Would be hard to diy-build any kind of discrete amplifier for less... but, still, buying a module, be it excellent, doesn't replace the act of creating your own, and the satisfaction when you get it to work 😉
Although, I have to admit, it's quite motivating to get an amp module, hack the power supply and a case in a few hours, and finish the whole project within a day 🙂 just did this with an STK086 chip amp for my subwoofer, because I didn't have time, and missed my low frequency response, after I burnt my class D amp:
clicky
djQUAN,
I think I already wrote to replace the triangle generator opamps with a function generator. I think it's also much better to replace the 2 filter coils in series per half-bridge with only one center-tapped coil. This way, the energy stored in the magnetic field can flow through the speaker during an asymmetric phase, and doesn't have to go through the diodes. Not sure though how the linearity will be. I can't try, unfortunately I damaged mine beyond repair... One day I'll make a new one.
When you choose MOSFETs, try to get some fast ones with short switching times, that still have reasonably low Rds_on. There seems to be a trade-off, but there are a few really fast high-power ones.
Cheers,
Felix
I think I'll stay with the op amp oscillator. it's very hard to find exotic components over here. my main concern is the availability of the IR2112's.
I have finished a small daughter board having SMT components. a LF347 and a LM339 quad comparator. enough for a stereo amp.
while testing, I noticed there is overlap with the two outputs. I assume this doesn't matter since the mosfets are "separated" by the inductor/s? also, clock freq is about 330kHz.
for the output mosfets, I was thinking 50N06's.
I have finished a small daughter board having SMT components. a LF347 and a LM339 quad comparator. enough for a stereo amp.
while testing, I noticed there is overlap with the two outputs. I assume this doesn't matter since the mosfets are "separated" by the inductor/s? also, clock freq is about 330kHz.
for the output mosfets, I was thinking 50N06's.
Hi,
actually, there's not only overlap, but both mosfets are meant to be on at exactly the same time. This is one feature of the BCA modulation - at zero input, both mosfets switch on amd off at the same time with 50% duty cycle - the modulation then antisymmetrically changes the duty cycle of the mosfets. Read the papers on the Crown website about BCA.
Due to the inductors between the mosfets, shoot-through doesn't occur - instead, the energy is stored in the magnetic field, and flows back to the rails over the diodes. BTW, I think it might be good to have a small cap in parallel with the diodes, maybe in series with a resistor to avoid oscillations, in order to reduce voltage spikes on the diodes, and temporarily store energy, until the diodes become conductive.
Oh, and function generators are not that hard to get - imho most electronic retailers have one. doesn't have to be the same I used. But with a proper SMD board, Opamps should also give good results. On my veroboard design, the triangles looked terribly noisy.
have fun,
Felix
actually, there's not only overlap, but both mosfets are meant to be on at exactly the same time. This is one feature of the BCA modulation - at zero input, both mosfets switch on amd off at the same time with 50% duty cycle - the modulation then antisymmetrically changes the duty cycle of the mosfets. Read the papers on the Crown website about BCA.
Due to the inductors between the mosfets, shoot-through doesn't occur - instead, the energy is stored in the magnetic field, and flows back to the rails over the diodes. BTW, I think it might be good to have a small cap in parallel with the diodes, maybe in series with a resistor to avoid oscillations, in order to reduce voltage spikes on the diodes, and temporarily store energy, until the diodes become conductive.
Oh, and function generators are not that hard to get - imho most electronic retailers have one. doesn't have to be the same I used. But with a proper SMD board, Opamps should also give good results. On my veroboard design, the triangles looked terribly noisy.
have fun,
Felix
can I use fast recovery diodes instead of schottkys? not sure if I can find 60V schottkys. fast recovery ones can go to 1000V.
for the inductors, the cores I have available are from computer SMPS's. the output filtering ones. I know these are powdered iron but they are big enough. I think. 🙂
the triangle wave that I got was clean but with a little ringing at the top. other than that, everything was fine.
for the output waveform, I got overlap only when the input goes positive. when it goes negative, there is some dead time.
for the inductors, the cores I have available are from computer SMPS's. the output filtering ones. I know these are powdered iron but they are big enough. I think. 🙂
the triangle wave that I got was clean but with a little ringing at the top. other than that, everything was fine.
for the output waveform, I got overlap only when the input goes positive. when it goes negative, there is some dead time.
I can't edit my post so........
the output I got is fine. turns out I read the scope wrong. 🙂
I still got 333kHz output, triangle but the peaks seem clipped.
output does overlap and conducts at the same time. and also gave the BCA article a little read.
the output I got is fine. turns out I read the scope wrong. 🙂
I still got 333kHz output, triangle but the peaks seem clipped.
output does overlap and conducts at the same time. and also gave the BCA article a little read.
ok i have s stupid question.
what is the deal with the Vgnd? and where is it connected on the comparator beacouse the symbols do not match the chip
what is the deal with the Vgnd? and where is it connected on the comparator beacouse the symbols do not match the chip
The VGnd stands for virtual Ground, and replaces the Ground of a real symmetric power supply (I wanted to drive the amp from a single sided supply). It is nothing but a stabilised voltage divider, generating a voltage exactly between the + and Gnd of the main supply. On the comparator, VGnd is connected to the Gnd pins of the chip (pin 3 and 8, according to the data sheet). It is a bit confusing in my schematic - I wanted to show more the function than the actual implementation, that's why I chose to use the generic comparator symbols.
It's better if you build it with a symmetric supply for the modulator and the power stage as well - some things with the logic of the mosfet drivers might change then, though.
djQuan, could you get your amp to work? I haven't done any work on mine. I recall that I had some heat problems at some stage I couldn't explain - just wondering how yours is doing.
It's better if you build it with a symmetric supply for the modulator and the power stage as well - some things with the logic of the mosfet drivers might change then, though.
djQuan, could you get your amp to work? I haven't done any work on mine. I recall that I had some heat problems at some stage I couldn't explain - just wondering how yours is doing.
Re: Here's one...
hi sfx
i am planning to make the class d amp (bca full bridge)
i have some questions::::
the o/p inductors--core size,wire dia and the number of turns?
its ferrite or powdered iron?
can irf540 be used?
if i stick the unit in my car,then how to obtain +35..do i need to construct smps or it can be done in a more simple way?
or alternatively..
can it be modded for as a dual supply version(i have a smps in my car)?how?
i will use it for sub replacing my tda729x series amps which are very huge(jus jus bec of heatsinks)
Sagar
sfx said:
hi sfx
i am planning to make the class d amp (bca full bridge)
i have some questions::::
the o/p inductors--core size,wire dia and the number of turns?
its ferrite or powdered iron?
can irf540 be used?
if i stick the unit in my car,then how to obtain +35..do i need to construct smps or it can be done in a more simple way?
or alternatively..
can it be modded for as a dual supply version(i have a smps in my car)?how?
i will use it for sub replacing my tda729x series amps which are very huge(jus jus bec of heatsinks)
Sagar
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