JLH1969 MOSFET Class A/AB amp

millwood

这线路用卡版的PCB可以搭.

yeah. just drop in the mosfets and everything else can be the same.

IRFP140可以用哪些管代

pretty much any power mosfets will do.

just be careful with those with "N" prefix (like irf540N or irf530N). they are designed for digital applications and don't have a wide safe operating area ("SOA") and can get burned out quickly.

I also had troubled with Fairchild FDP3682 - as it doesn't seem to be thermally stable with that particular mosfet.

My favorite is IRF540 (IRF), FQA25N50 (Fairchild), and IRFP140 (IRF).

millwood

heatsink: I am currentlying use an unfanned Pentium 2 heatsink for my version. no problem in the winter or summer, as long as the amp idles at less than 100ma.

with a fan (12v computer fan attached to the heatsink), I can easily dial up the idle current to 200ma and the heatsink remains luke warm.

cencal

挖个坑

qjdj

我弄了块较大的散热片，听400ma中。 耳朵不好，听不出小电流和大电流的明显区别。

民主

楼主能不能多点仿真指导？

qjdj

这个电路比较成熟了，也很稳定，你可以试试用他这种输入级偏置和我图中那种模仿传统1969的偏置方式比较。其他部分没有什么大的改变了。
有点差别，我推动管用的三极管，场管做推动我没有试过。

民主

原帖由 qjdj 于 2008-4-22 23:59 发表
这个电路比较成熟了，也很稳定，你可以试试用他这种输入级偏置和我图中那种模仿传统1969的偏置方式比较。其他部分没有什么大的改变了。
有点差别，我推动管用的三极管，场管做推动我没有试过。

我也是试验了场效应管输出

忘记试验场效应管推动了  后来板子被拆了 才看到这个图 后悔没玩到

swq007

有空我也玩玩这个

qjdj

原帖由 民主 于 2008-4-23 00:13 发表



我也是试验了场效应管输出

忘记试验场效应管推动了  后来板子被拆了 才看到这个图 后悔没玩到

如果你出板子，那就有大把的机会试了。只需要调整元件参数，pcb一样的。

millwood

原帖由 民主 于 2008-4-22 23:55 发表 楼主能不能多点仿真指导？

here is the swcad file for simulation purposes, in winrar format.

and here is the link to download the software itself: http://www.linear.com/designtools/software/switchercad.jsp, click on the 2nd link that reads "No thanks, just download the software". and then install it and you are in.

it is a small download (less than 8MB).

qjdj

我也把multisim画的这个电路的仿真放上来吧，有兴趣的可以用用。
mosfet1969.rar (88.2 KB, 下载次数: 302)

2008-4-23 18:55 上传

点击文件名下载附件

DarkHorse

我以前用MULTISIM2001仿真该电路时有奇怪现象,输入越低的电平信号,失真就越大;
静态电流调得越高,失真也越大...
奇怪ING!

millwood

原帖由 DarkHorse 于 2008-4-23 19:16 发表
我以前用MULTISIM2001仿真该电路时有奇怪现象,输入越低的电平信号,失真就越大;

that may happen if you have cross-over distortion - the idle current is too small and the amp works in Class C.

and most amps have higher distortion at very low input signal.

静态电流调得越高,失真也越大...
奇怪ING!

that is a little weird. One possible reason is that the gm for the mosfets is too small. this is more likely with lateral mosfets (Hitachi / Toshiba). Most of the power mosfets we use today (IRF types for example) are vertical mosfets and they have higher gm than lateral mosfets.

millwood

there is also a slightly different version for jlh1969m, as shown below, with the addition of R15.

in the previous version, the lower mosfet is turned on by the current going through R2 (220ohm resistor). and the upper mosfet is turned on via the voltage over the boostrap network. so the lower mosfet is more "current drive". and the upper mosfet is more "voltage drive". some people don't like that symmetry.

the addition of R15 changes that. Now, the upper mosfet is turned on by the current going through R15 (220ohm resistor) as well. This version is closest to the original JLH1969 as both transistors in that amp are turned on via current.

the addition of R15 can be easily done on the PCB.

if you go down this route, you will need to substantially reduce R1 and the current and power dissipation over R1 / R14 is now substantially increased. so use beefier / larger resistors there.

I myself have not found any audioable benefits to this particular version.

音响DSP

我看了下相关的连接，还是喜欢差分输入的版本。有其他用途，打算用运放做个驱动，大环路电压副反馈，AB类，功率大些。

HIFI2008

millwood 老师，你好～

你在#254发的图中，输入级用A970、推动级用BD139或者是D669，这样合适吗？？

输出电容，这么大容量的，一般使用什么型号好？？看来除了滤波电解没有哪种有这么高的容量了……

HIFI2008

此外，这个版本需要增加茹贝尔网络吗？图中的 R6 是不是8欧负载的意思？？还是需要上的电阻？？

millwood

hifi2008: I am not as familiar with japanese / european transistors but my first glance on the datasheets suggest that 2sa970 will be more than sufficient for the front end, and 2sd669 for the phase spliter.

I have personally used bd139 so I know it works. But make sure that you use a small heatsink on them just to be safe.

a zobel network would help but I haven't needed it in mine yet.

yes, R6 is the speaker.

millwood

on the output capacitor, I used a nichicon myself.

zjtanym

记号，很有兴趣，希望有套件购买，那位老大赶快推出。