Schematic for Fluke RPM80 Inductive Pickup (re: thread240-431670)
Schematic for Fluke RPM80 Inductive Pickup (re: thread240-431670)
(OP)
thread240-431670: Sparkplug Clamp Pickup Sensor Circuit Fluke RPM80
Regarding the previous (now closed) post:
https://www.eng-tips.com/viewthread.cfm?qid=431670
"Sparkplug Clamp Pickup Sensor Circuit Fluke RPM80"
I found the thread discussing internals of the Fluke RPM80 pickup and there are a lot of photos but I didn't see an actual schematic.
I drew up what I think is the schematic but I wanted to confirm since I may have misinterpreted the photos
Also, I am not sure I correctly read the value of the Capacitor (does it say K1G / 821J ? I'm not sure I read the first digit (8?) correctly).
So I was hoping the original author of that post (MRSSPOCK) could comment... thanks!

Regarding the previous (now closed) post:
https://www.eng-tips.com/viewthread.cfm?qid=431670
"Sparkplug Clamp Pickup Sensor Circuit Fluke RPM80"
I found the thread discussing internals of the Fluke RPM80 pickup and there are a lot of photos but I didn't see an actual schematic.
I drew up what I think is the schematic but I wanted to confirm since I may have misinterpreted the photos
Also, I am not sure I correctly read the value of the Capacitor (does it say K1G / 821J ? I'm not sure I read the first digit (8?) correctly).
So I was hoping the original author of that post (MRSSPOCK) could comment... thanks!

RE: Schematic for Fluke RPM80 Inductive Pickup (re: thread240-431670)
I looked at the picture and the core is a UI-core style with the winding on a leg of the U and the I on the clamp part to close the magnetic path. There are a number of different ferrites with different mu (permeability), so that is a minor mystery, but may not be too important.
The pickup is a transformer where the spark wire is a 1-turn input.
RE: Schematic for Fluke RPM80 Inductive Pickup (re: thread240-431670)
Yes the schematic looked reasonable and made sense to me as well, but
I could not read some of the photos clearly in the original post.
Especially the first digit on the value on the capacitor.
A few years back, I built an inductive pickup from part of an E-shaped, laminated iron transformer,
where I cut off one side, and I used the secondary winding and with a removable end.
I think it has something like 400 turns of wire.
I'm pretty sure the output voltage is much higher than I need.
So high, that I don't even need to connect both sides of the output coil to my timing light circuit
which has a 555-timer one-shot/pulse-stretcher which turns on a Triac to fire a trigger coil of a flash
I pulled out of an old Fujifilm disposible-camera.
So I might try this updated circuit for the front-end pickup.