[TechAssist] Re: Trouble with 10x Probe
- From: "John at Main TV" <maintv2004@xxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Thu, 17 Mar 2005 12:16:10 -0700
I always make my own scope probes. I do not like what is available except
the HP probes which are very expensive. It sounds like you got it figured
out. One suggestion regarding the trimmer cap. I use a small disk
capacitor of slightly less value than what is required, then add a short
length of 2 conductor wire, something like the wire used for earphones,
very fine. Solder one conductor to each side of the capacitor. I start with
about 6 inches of wire, then gradually shorten until I reach the correct
capacitance. It may take a couple tries to get it right. That way you can
put shrinkable tubing over it and it is very compact. John.
John Mielke
Main TV
Longmont,Co 80501
303 776 6955
303 776 0792 fax
maintv2004@xxxxxxxxxxx
www.longmontmaintv.com
----- Original Message -----
From: "Bil Green" <tv.vcrrepair@xxxxxxxxxxx>
To: "Tel-Tek" <techassist@xxxxxxxxxxxxx>
Sent: Thursday, March 17, 2005 3:45 AM
Subject: [TechAssist] Re: Trouble with 10x Probe
> Thanks everyone! Placing 20pF across the 9M resistor fixed the
> problem. A trimmer cap (when I get one) will improve the accuracy.
>
> Bil
>
> PC 1000
> Mammoth Lakes, CA
> 760-924-1000
> M-Pulse 5000 magnetic pulse generator
>
>
> Wednesday, March 16, 2005, 6:56:54 PM, you wrote:
>
> TT> Sounds like you need to upgrade Bil. :-)
>
> TT> Especially if you are now doing this on a "full" time Basis.
>
> TT> Remember..Higher Voltage doesn't mean a "Higher" bottom line.
(kidding) :-P
>
> TT> -Ed-
>
> TT> Bil Green wrote:
>
> >>I am trying to find just what's needed to build a 10x adapter for a
> >>scope probe.
> >>
> >>I need to measure up to 2kV AC PP and it's hard to find one that high
> >>(and I need it right anyway). I will be checking a 5kHz AC voltage.
> >>
> >>My scope has a 1M input impedance, so adding 9M in series should do
> >>the trick. But that doesn't work! The voltage reading is far less
> >>than 10% measuring 250V PP horizontal signals (TV analyst). I tried
> >>a carbon composition and carbon film resistor.
> >>
> >>Same problem using it with my PP voltmeter (designed for testing TVs,
> >>and also has a 1M input impedance).
> >>
> >>The 10x probe for my scope went bad (reads way too low when set for
> >>10x). I was using it to measure an AC voltage which was over 2,000V
> >>PP and didn't know that the probe was only rated at 600V.
> >>
> >>Bil
> >>
> >>PC 1000
> >>Mammoth Lakes, CA
> >>760-924-1000
> >>M-Pulse 5000 magnetic pulse generator
> >>
>
>>--------------------------------------------------------------------------
---
> >>This Email List is Public. Remove: http://www.tech-assist.org/remove.htm
> >>Lost Password: http://www.tech-assist.org and select "Login Problems?".
> >>Email Archives: //www.freelists.org/archives/techassist/
> >>
> >>
> >>
>
> --------------------------------------------------------------------------
---
> This Email List is Public. Remove: http://www.tech-assist.org/remove.htm
> Lost Password: http://www.tech-assist.org and select "Login Problems?".
> Email Archives: //www.freelists.org/archives/techassist/
>
-----------------------------------------------------------------------------
This Email List is Public. Remove: http://www.tech-assist.org/remove.htm
Lost Password: http://www.tech-assist.org and select "Login Problems?".
Email Archives: //www.freelists.org/archives/techassist/
Other related posts:
