Scale able class D 1250W UCD style and Non-UCD style - PCB Ready. Tested.

[stewin]

irf540 or irf540z?

two channels one is two pairs irf540 the other is two pairs irf540n

 

[norazmi]

irf540n will work more good or more better with irf540z

 

[pergo]

IRF540 and 540A are for linear operation
IRF540N are good for switching but at low frequency.
IRF540Z are very good for high frequency switching.

Respect of the N version, the Z version have less Rds_on, less recovery charge (10 times less the N version), less Recovery time, less Ciss and Gate Charge.

For full-range class D, i suggest the Z version.

 

[stewin]

but guys the distortion is serious at low volumes if i dont reach a certain volume the amp will not work. i even think there is a ceramic capacitor missing??

 

[stewin]

has any one tried the non ucd version?

 

[pipiripao]

has any one tried the non ucd version?

That schematic has an error,
Q5 is inverted,
Q5 Emisor goes to Supply rail.
Q5 Colector goes to Q3 Base.

regards!

 

[stewin]

I have replaced the feedback. The transistor bit I had aready changed according to my schema. I have failed to solve the problem so I removed the 56k post feedback resistor and put a UCD feedback exactly like the one found in UCD 25 to 1200. Now everything is ok & there's no noise or distortion. I will post schema. I hope the non UCD will work, because I liked the classD 200 rms watts clarity.

Now the amp is working perfectly. The only thing I've replaced is the feedback from non UCD to UCD

 

[apollo10]

If i want to use IRFB4020 what value should i use for the gate resistors? P.s Nice project Stewin,i hope that you will post the new diagram with the replaced feedback.
Good luck.

 

[stewin]

If i want to use IRFB4020 what value should i use for the gate resistors? P.s Nice project Stewin,i hope that you will post the new diagram with the replaced feedback.
Good luck.

also the aux supply for 12vlts i want to change because in post filter (non ucd) it doesn't work well it drops to 7volts but in pre filter mode (ucd) it works well.

 

[apollo10]

How much power it can deliver this project in 8 ohm at 90v (with all pairs of IRFB4227) ?

 

[stewin]

it is now working even in non ucd mode the problem was the tl431 12vlts aux mode . i have replaced with a 15vlts zeener diode and 100nf and still use fet in aux switching.
>>>>>> but in non ucd it is louder and the output fets get hot unlike in ucd mode they are cold .but if you replace the c9 820p to 4.7nf they become cool again -)-)-)

 

[apollo10]

I hope that you resolve this issue, and keep us posted.
Good luck.

 

[norazmi]

yes because u lower the freq, improper gate resistor will also cause mosfet heat fast. hehe. Stewin look at discrete ucd thread, i did OCP protection successfully, and it can be apply with any ucd and non ucd amp . If u drive more than 1 pair with totem pole, u need enough aux supply, i`m always mention that before :"::

 

[norazmi]

apollo irfb4020 u can set gate resistor as low as 10-15 ohm or even lower for low supply and low load.

 

[apollo10]

i'm interested to obtain 1000w in 8ohm with a source of 90-100v with any kind of IRFB's.

 

[stewin]

This non UCD amp is amazing . After replacing th 860pf with 10nf, my voltage is +/-45vlts at 10amperes and I'm not using a heat sink for my output fets are cold and the amp is loud, you can think that the amp is not powered. My speaker is 6ohms for 8" base and 4ohms for 4" midrange. But i've added a capacitor 47uf for the mid speaker. i'm only using one channel directly from the pc without op amp or any processing.

>>>My only challange is the EEI core from the PC power supply. I'm using 18turns and i've put a piece of CD to form gap. It produces A LOT of heat. Even the white masking tape has changed colour to brownish. Please advice on core. I will post pictures later.

 

[norazmi]

LOL .. Apollo 1000W in 8 ohm such as big power amp, Big PSU, Big caps bank and parallel mosfet with totem pole to gain more current and cool at high voltage. Need very good trace that special pcb design for that power range, tripple stack T106-2 iron powder core, big coil filter etc etc... . To Apollo, u dont need to drive power amp at high voltage such as +/- 90 vdc, u can use full bridge mode at +/- 60 vdc, totem pole of course. The importat its need to be simulate with LTspice first .

 

[norazmi]

Stewin need more bigger EI ferrite core, seems that core cant hold more current pass through it.

 

[apollo10]

I was thinking to use a higher voltage because i allready have a toroidal transformmer and because in the case of using a smps at this volge, the current will be smaller than using 60v and result a much thiner wire to work with on the secondary side of ETD. Now i'm a little busy, but i want to collect all the necesary informations and build this amp next month
In conclusion, how much power can deliver this amp with 4 pairs of 4227 ? i'm just curious

 

[paskal]

To paskal:

Its very hard now to change Relay because its all very tite and close, but I'll try... If I do that, your output coil have to be external from amp board true the wires, because I have to move relays down, closer to heatsink...

no problem brother. don't need to do so now that i've found a couple of 24v DPDT relays from my way older power amp project.

How much power it can deliver this project in 8 ohm at 90v (with all pairs of IRFB4227) ?

at 90v you'll have ~63vrms. if there's no shortage of current you'll get 496w rms into 8 ohm. for such high power i think you're better off running bridged into 8 ohm. reduces the bus pumping effect and should ease the load on your ground return current. in my experience it'll also help reduce possibility of ground loop problem.

like norazmi suggestion, you're better off running full bridged at 63v into 8 ohm. you'll still get ~1000w rms.