d********k
发帖数: 701 | 1 我一个MX revolution鼠标，充电有问题，有个网站说在充电底座上串联三个10ohm电阻
就可以。我试一下，确实好一些，可是用一会，电阻就开始高温发热。
我买的电阻是1/8 watts，有个youtube录像说他用 1/4 watts，都是10ohm。
请问这时候，电阻功率越大，发热越少吗？
谢谢 |
|
D**********s
发帖数: 3139 | 2 我不知道你现在用啥前端，不过老的meridian和mark levinson前级输出阻抗也就是
50ohm和10ohm，Vpp在600ohm的时候也可以到10V以上，HD650配这些前级只需要买一根
这个，在瞎花钱之前为啥不先试试自己前端的水呢？ |
|
y****o
发帖数: 666 | 3 首先usb电压 = 5 + - 0.25V这个是标准，别说苹果就算是鸭梨牌的也要遵守
开口电压定死5V，有两个电阻，一个1ohm，一个10ohm，试问这个“但iPhone/iPad充电
器有“主动”预防电路”如何实现对两个电阻5A电流输出？
我不否认电池的充电电路通过信号端电压判断充电器功率，我第一帖里说的很明白：使
用iphone充电器为ipad充电可能会损坏充电器，因为iphone充电器功率不够。我强调的
是使用额定功率5W的充电器给10W的设备供电有安全隐患。这就好比体外射精避孕，大
部分情况安全，可万一有点意外就出事故了 |
|
n***r
发帖数: 25 | 4 youfellow made very good points here. improve chopper frequency to move
signal away from flicker noise and use lockin amplifier to detect signal.
I guess LZ's major problem is: even TIA is saturated, the signal is still
too weak.
If Idc=1A, Iac=1uA, with R=10ohm Vdc=10V, Vac=10uV.
Vac is easily burried in the noise floor. You may use Lock-in Amplifier to
get some signal out, you wont get great SNR.
So the solution is to seperate Idc from Iac before converting into Voltage.
Of course you can't f |
|
n***r
发帖数: 25 | 5 Let me go over with you again.
;the gain of the amp is 500k/10=50k x, approaching most opamp's open loop
;gain, if not more.
Let's replace the 10 ohm with 0 ohm. Will your inverting amplifier theory
work? will the transimpedance amplifier work? Admit it, you were misled by
the 10ohm resistor then you came up with a wrong AC bandwith analysis.
;at that king of gain, the bandwidth of the opamp is very low, likely <10hz -
;check out the opamp's datasheet.
Wrong! The bandwidth of the Transimpedance |
|
l***g
发帖数: 1035 | 6 经常见到dsp或者cpld 的 dio 有resistor array 10ohm-50ohm。 记得是和噪声有关。
那位有相关的参考资料么？一般多高速的信号，时钟用的上？ |
|
