Capacitor Tester!

grapplesaw

Veteran and General Yakker
Joined
Aug 13, 2014
Messages
2,398
Location
Vancouver
Tagline
---
#42
So general question

I built this rotary switch with 11 different capacitance values to choose from.

I thought since I posted about my tester I would see how it measures. Well it came up with 180pf in the open setting and went up from there not following the values of each. So this tells me the switch has capacitance and somehow piggybacking additional capacitance from all the caps not in circuit.

any thoughts on this anyone? 857B8A47-8E4D-4FBF-8C10-B7676D3E5366.png
 

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
12,151
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#43
So general question

I built this rotary switch with 11 different capacitance values to choose from.

I thought since I posted about my tester I would see how it measures. Well it came up with 180pf in the open setting and went up from there not following the values of each. So this tells me the switch has capacitance and somehow piggybacking additional capacitance from all the caps not in circuit.

any thoughts on this anyone? View attachment 71404
Classic problem you face Glen. When working with tiny values of capacitance layout has to be carefully considered. It is hard to do what you are doing with a very large selector switch like that plus all the wires. Since you only have one selector, I am surmising it sits downstream from all your relay logic.
 

grapplesaw

Veteran and General Yakker
Joined
Aug 13, 2014
Messages
2,398
Location
Vancouver
Tagline
---
#44
Classic problem you face Glen. When working with tiny values of capacitance layout has to be carefully considered. It is hard to do what you are doing with a very large selector switch like that plus all the wires. Since you only have one selector, I am surmising it sits downstream from all your relay logic.
Hi joe
yes it is down stream, actually it’s now disabled. I could use a much smaller unit with 6 values. I have this in the carver but took it out of the sound path. I will test that one and see how it looks. It’s a gray hill about 5/8” round 74417C9B-C5A2-4351-98A9-D5D79D15A9DE.png 2289552A-16A7-480C-A3BD-5F5069345BED.jpeg
 

Attachments

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
12,151
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#45
Hi joe
yes it is down stream, actually it’s now disabled. I could use a much smaller unit with 6 values. I have this in the carver but took it out of the sound path. I will test that one and see how it looks. It’s a gray hill about 5/8” round View attachment 71405 View attachment 71406
Have you had a chance to measure the relay logic without anything downstream from it. It would be good to know what you are fighting with just the wiring and the layout of that board. I am pretty sure they were not thinking about their layout capacitance when they designed that board.
 

grapplesaw

Veteran and General Yakker
Joined
Aug 13, 2014
Messages
2,398
Location
Vancouver
Tagline
---
#46
Have you had a chance to measure the relay logic without anything downstream from it. It would be good to know what you are fighting with just the wiring and the layout of that board. I am pretty sure they were not thinking about their layout capacitance when they designed that board.
i did a quick check and there was about 130pf in that Joe. I’ve also got to measure the interconnects. I do have a blank board to measure without wiring. I used light gauge 28 to wire the box
 

grapplesaw

Veteran and General Yakker
Joined
Aug 13, 2014
Messages
2,398
Location
Vancouver
Tagline
---
#47
I have to correct all readings
I find the tester even though has been mulled for lead capacitance it reads 150pf when tested uphooked to anything so all values are off
The relay switch is only 12pf
The 5’ interconnects I need are are high at 350pf so building a pair out of rg316 to see what that may yield
 

Skratch

Chief Journeyman
Joined
Dec 27, 2011
Messages
1,002
Location
Huntley Il.
Tagline
Life is short, so take your time
#48
I have to correct all readings
I find the tester even though has been mulled for lead capacitance it reads 150pf when tested uphooked to anything so all values are off
The relay switch is only 12pf
The 5’ interconnects I need are are high at 350pf so building a pair out of rg316 to see what that may yield
You've created a monster
 

e30m3mon

Journeyman
Joined
Feb 9, 2013
Messages
464
Location
Hudson Valley NY
Tagline
---
#51
I have to correct all readings
I find the tester even though has been mulled for lead capacitance it reads 150pf when tested uphooked to anything so all values are off
The relay switch is only 12pf
The 5’ interconnects I need are are high at 350pf so building a pair out of rg316 to see what that may yield
I can see a run on RG316 now :)
 

grapplesaw

Veteran and General Yakker
Joined
Aug 13, 2014
Messages
2,398
Location
Vancouver
Tagline
---
#52
The Mogami Neglex quad mic cable is cheap and low capacitance as I recall...
Hi Jim
Thanks for that
I have some low capacitance four wire that I used for a few interconnects and what I am using in this setup. I have found that with the shield bonded one end only to ground wire there is more than double the capacitance than without it bonded I will make a couple up anshould see about 100pf /m

I also have some low capacitance two wire which also displays the much lower capacitance without bonding the shield at about 120pf / m

not sure where I am going but it beats going down the rabbit hole
 

grapplesaw

Veteran and General Yakker
Joined
Aug 13, 2014
Messages
2,398
Location
Vancouver
Tagline
---
#57
I'm surprised that there is not a wireless cartridge and Bluetooth receiver yet
Will not make the cut. Bluetooth not a very flat transport I’d say Im no happy with the sound of my iPhone through Bluetooth on the system compared to lp or cd sourced at the pre amp
Heh it’s just my opinion I’m wrong a lot of the time.
 
Top