The schematics of all solid-state CDV-700 Geiger Counters are presented here in a manner that allows one to A) easily understand how the respective units function, and B) very quickly gauge any differences that exist between the various units. Print up all the stock schematics and compare—it's interesting to see how similar they all are.

(Models 1 through 3 are all vacuum tube models and didn't grab my attention as easily, alas.)

• CDV-700 Anton 5 & 6

• CDV-700 ENi 6b Simplified
  Redrawn ENi so anyone can understand its operation
  
• CDV-700 ENi 6b
  
• CDV-700 ENi 6b Corey's
  Here's a modified ENi with pot-per-range calibration and other features
  
• CDV-700 ENi 6b Rotary Switch
  The ENi stock switch—there's more there than you thought
  
• CDV-700 ENi 6b Rotary Switch MOD
  Install a new switch and add pot-per-range calibration
  
• CDV-700M ENi 6b
  The Factory modified version with an alpha-sensitive probe

• CDV-700 Lionel 6B
  
• GEO's LENi
  The LENi is a Lionel'ized ENi 6B by George Dowell (k0ff). This
  redrawn schematic omitts certain errors found in other versions.

• CDV-700 Universal Atomics 4

• CDV-700 Victoreen 6 & 6A
  
• CDV-700 Victoreen 6B
  
• CDV-700 Victoreen 6B HV Adjustment
  A table showing exactly what the HV adjustment pot does
• CDV-700 Victoreen 6B Corey's
  Modified Victoreen 6B with pot-per-range calibration and other features
  
• CDV-700 Victoreen '6C'
  Wanna make your Victoreen 6B work on only two D cells?

• CDV-700 Meter Scale
  Here's a meter scale for third party meter movements

• CDV-705 - 1 Overview
  Make an external speaker with the looks and feel of a
  real CDV-705 using a CDV-750 Dosimeter Charger!
• CDV-705 - 2 Interior
  
• CDV-705 - 3 Case Back
  

• CDV-715 Landers, Frary & Clark 1A Survey Meter
  
• CDV-715 Victoreen 1A Survey Meter
  
• CDV-715 Victoreen 1B Survey Meter

• CDV-750 Dosimeter Chargers
  Here are the schematics of five different models for comparison sake

• Detector Overload Circuit
  Add an LED for indicating a saturated GM tube

• Pulser - 1 Mechanical
  Bill Beamon's (kd4fnc) Pulser/HV Test-Set with a few
  mods, packaged into a nice little commercial case.
  
• Pulser - 2 Schematic
  
• Pulser - 3 Layout
  

• Pulser - El Cheapo
  This one sports only only pulse rate---3600CPM, but can be built from items already lying around in your junk box.

• Scintillator - Preamp 1
  Charlie Thompson's (w5cdt) preamp and metering circuit
• Scintillator - Preamp 2
  GEO's (k0ff) in-line preamp
• Scintillator - Preamp 3
  Collection of five scintillator preamps, including two from Ludlum, two from GEO, and one from Charlie Thomspon. I breadboarded all five versions side by side, and liked GEO's in-line circuit the best.
• Scintillator - Square Bicron
  Schematic of GEO's (k0ff) square scint

• Scintillator in a CDV-715 - 1
  Main circuit. This is a homebrew scintillator packaged in a CDV-715 can, which uses GEO's square Bicron probe. The meter, rotary switch, and control remain. The original board gets tossed and a new one replaces it.
• Scintillator in a CDV-715 - 2
  Power supply
• Scintillator in a CDV-715 - 3
  Battery check circuit
• Scintillator in a CDV-715 - 4
  Board layout
• Scintillator in a CDV-715 - 5
  Plateau 2
• Scintillator in a CDV-715 - 6
  Plateau 5
• Scintillator in a CDV-715 - 7
  Miscellaneous
  

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For additional information, follow these links:

• CDV-700 schematics as drawn by draftsmen and not engineers—UGH!
  (I appreciate these manuals, certainly, but who hired the bozos that drew up their respective schematics?)
  
• Civil Defense Museum webpage on CDV-700s—A great page!
  
• Yahoo's Tech Group—CDV-700 Club
  
• Yahoo's Tech Group—Geiger Counter Enthusiasts
  

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since 17JUL07

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Corey Hatch <hatch@cs.utah.edu>