如图 我是这样测 1 uH以下的电感的

e3po

原帖由 millwood 于 2011-2-7 23:57 发表
what's the amplitude of the output, from the collector and the emitter?

Normally 1/2 Vcc,  but drops to 100~200mV when above 150MHz.

millwood

take a look at Yates' approach:

http://www.vk2zay.net/article/132

however, I was never able to get it to work. but you may have better luck at that.

laghi

原帖由 millwood 于 2011-2-17 03:15 发表
take a look at Yates' approach:

http://www.vk2zay.net/article/132

however, I was never able to get it to work. but you may have better luck at that.

楼上朋友是不是和我的电路相似

e3po

原帖由 millwood 于 2011-2-17 03:15 发表
take a look at Yates' approach:

http://www.vk2zay.net/article/132

however, I was never able to get it to work. but you may have better luck at that.

thank you for your input!
I'd been busy taking care of my kid these days,

sorry for not being able to response in time.

millwood

don't worry, e3p0.

I haven't been able to get that to work but I gut some mc1648 (actually the high speed ecl version of it) on the way and it looks like the same topologically. I will let you know how it goes.

e3po

原帖由 millwood 于 2011-3-11 05:22 发表
don't worry, e3p0.

I haven't been able to get that to work but I gut some mc1648 (actually the high speed ecl version of it) on the way and it looks like the same topologically. I will let you know ...

Waiting for your good news....

millwood

I finally got it working.


here is my schematic.

L1 is the inductor you wish to measure. C1 is the capacitor that forms a lc tank with L1.

R1 determines the bias current for the oscillator.

Q1/Q2 forms an oscillator.

the key to this is to use a low R1: Yates used figures as high as 100K but I found out that mine oscillates reliably at under 10k.

I also found out that distributed capacitance / inductance is quite significant: without C1, and short L1, the circuit oscillates at around 20Mhz, all by itself.

enjoy.

e3po

I finally got it working.

here is my schematic.
millwood 发表于 26/6/2011 11:12

    hmmmm,   it seems your picture is kinda transparent   :p

e3po

I finally got it working.


here is my schematic.

L1 is the inductor you wish to measure. C1 i ...
millwood 发表于 26/6/2011 11:12

       wow,  that work great under LTspice











如果用 2SC3355  2SC3356  BFR93A 这些微波管应该可以减小结电容的影响， 或者提高电源电压。

millwood

it is a little bit simpler than the colpitts oscillator you posted earlier. However, because of the miller capacitance, it doesn't oscillate at as high of a frequency as yours does.

e3po

it is a little bit simpler than the colpitts oscillator you posted earlier. However, because of the  ...
millwood 发表于 26/6/2011 15:23

              I'll build one in real when I have time.  The waveform seems to be better than that of the Colpitts.

millwood

The waveform seems to be better than that of the Colpitts.

not sure. the wave form above 1Mhz is fairly sinuous. below 1Mhz, it is a square wave.

唐老鸭

越看越糊涂了，50Mhz的数字示波器测量大于50兆的信号哪能有准确的结果呢？电路设计的也过于简单了，呵呵，醒醒吧，哥们。

e3po

越看越糊涂了，50Mhz的数字示波器测量大于50兆的信号哪能有准确的结果呢？电路设计的也过于简单了，呵呵，醒 ...
唐老鸭 发表于 27/6/2011 09:36

        多谢您的提醒！

         RIGOL 的50MHZ 示波器能超频到 100MHZ， 内置的硬件频率计测量频率能到 300MHZ， 是实践证明了的。

        整个 FM 88~108 MHZ都能工作得很好， 波形和频率测量都能帮得上忙。

       不才用 RIGOL 50MHZ 示波器调好无线话筒的频率， 再用数调收音机印证， 分毫不差。

       如果您手头有闲置的  RIGOL 的 1052E 示波器，  不妨低价出了。


      另外， 窃以为振荡电路并不复杂， 两个晶体管够了， 如果您有更高级的振荡电路不妨分享一下。  不才也可以学习一下新的东西。

e3po

      JFET 的波形为什么要好过 BJT 很多呢 ？？