Many record changers can automatically sense the size of the record it is playing. Here is a list of the different methods used, and
how each one determines the kinds of stacks of records it can play.
| |
| GROUP |
METHOD |
HOW IT WORKS |
RECORD ORDER REQUIRED |
SAMPLE CHANGER PHOTO |
N
O
S
E
N
S
O
R |
Size Switch |
The user selects the size of the record by moving a control. |
Two, three, or four sizes. Only one size allowed in the stack.
Plays single record on turntable.
Sample is
Dual 1209
3-size knob on the right
|
|
| Speed and Size Switch |
The user selects the size and the speed of the record by moving one control. Usually some speed-size combinations are not available.
This unit allows 7" 33, 10" 33, 12" 33, 7" 45, & 12" 78. |
Two or three sizes. Only one size allowed in the stack.
Plays single record on turntable.
Sample is
Garrard SL-72B
knob on the left
|
|
| Record Shelf Position |
The user selects the size of the record by setting the side shelf to fit the records.
|
Two or three sizes. Only one size allowed in the stack.
Plays single record on turntable.
Sample is
Philco M-22
turn shelf on the left
|
|
| Spindle Selected Size |
The user selects the size of the record by changing spindles. Each diameter and hole size has a different spindle. The spindles slope
different amounts, and the lower ends of the spindles are different lengths, to select the arm setdown point.
|
Two or three sizes. Only one size allowed in the stack.
Plays single record on turntable.
Sample is
Milwaukee-Erwood 11600
the spindle is changed
|
|
| |
| GROUP |
METHOD |
HOW IT WORKS |
RECORD ORDER REQUIRED |
SAMPLE CHANGER PHOTO |
T
U
R
N
T
A
B
L
E
S
E
N
S
O
R |
Rising Feelers |
The first record on the turntable is sensed repeatedly for the entire stack. Sensors mounted in the turntable or beside it detect
the first record. The record depresses the sensors according to its size. |
Three sizes. Only one size allowed in the stack.****
Plays single record on turntable.
Sample is
PE-2040
pins in turntable and near rim
|
|
| Swinging Feeler |
Swinging feeler moves in to touch the edge of the first record on turntable.
Must have small turntable. |
Three sizes. Only one size allowed in the stack.
Plays single record on turntable.
Sample is
Philips AG 1116
feeler in curved slot
|
|
| Hole Size Feeler |
A rising feeler rises 1/2" from the center of the record. If it touches a record, it plays 12" 33.
If it does not touch a record, it plays 7" 45.
A slot in the 45 spindle lets the feeler pass through it.
Plays only 12" 33 and 7" 45. |
Two sizes. Only one size allowed in the stack. ****
Plays single record on turntable.
Sample is
Magnavox Micro-Mini W712
feeler in turntable near center
|
|
| 3-Size Turntable Arm Scan |
The pickup arm moves down, and then inward to touch the edge of the first record on turntable. If it does not find a record,
7" operation is selected. Then the arm rises, moves inward, and sets down on the record.
Must have small turntable. |
Three sizes. Only one size allowed in the stack.
Plays single record on turntable.
Sample is
Philips (unknown model)
protrusion on pickup arm
|
|
| |
| GROUP |
METHOD |
HOW IT WORKS |
RECORD ORDER REQUIRED |
SAMPLE CHANGER PHOTO |
D
R
O
P
S
E
N
S
O
R |
Droplever |
The falling record pushes the feeler down different amounts, or does not strike the feeler, selecting different record sizes. |
Two or three sizes can be intermixed in any order in the stack.
No single record on turntable.
Sample is
Collaro Continental
feeler protruding from slot
|
|
| Tilting Feeler |
The feeler, shaped like the number 4, tilts forward before the record drops. Then the falling record strikes the sloped edge and
pushes the feeler back different amounts, or does not strike the feeler, selecting different record sizes. |
Two or three sizes can be intermixed in any order in the stack.***
No single record on turntable.
Sample is
Glaser-Steers 77
feeler is behind overarm
|
|
| Semaphore |
The feeler axle is vertical. The falling record rotates the feeler away from the spindle different amounts, or does not
strike the feeler, selecting different record sizes. |
Three sizes can be intermixed in any order in the stack.***
No single record on turntable.
Sample is
Garrard AT-60
curved object left of overarm
|
|
| |
| GROUP |
METHOD |
HOW IT WORKS |
RECORD ORDER REQUIRED |
SAMPLE CHANGER PHOTO |
S
T
A
C
K
S
E
N
S
O
R |
Index Arm |
The index arm touches the edge of the stack before the record drops, then backs off so the record can drop. If no record is found,
automatic shutoff occurs. |
Three sizes. Larger records must be below smaller records.
No single record on turntable.
Sample is
Webster 100
arm left of overarm
|
|
| 3-Size Arm Scan |
The pickup arm head touches the edge of the stack before the record drops, then backs off so the record can drop. If no record is found,
automatic shutoff occurs. |
Three sizes. Larger records must be below smaller records.
No single record on turntable.
Sample is
Collaro PH1252
protrusion on pickup arm
|
|
| Pickup Arm Scan |
The pickup arm touches the edge of the stack before the record drops, then backs off so the record can drop. If no record is found,
automatic shutoff occurs. The use of a slipclutch allows odd-sized records to be played.
The photo shows the sensing action.
|
12" to 6". Larger records must be below smaller records.
No single record on turntable.
Sample is
Collaro Conquest
protrusion on pickup arm
|
|
| |
| GROUP |
METHOD |
HOW IT WORKS |
RECORD ORDER REQUIRED |
SAMPLE CHANGER PHOTO |
S
E
P
A
R
A
T
E
R
E
C
O
R
D
S
E
N
S
O
R |
Pickup Arm Scan on Lowered Record |
The record lowers about half an inch. Then the pickup arm touches the separated record. It then backs off so the record
can lower to the turntable. If no record is found, automatic shutoff occurs. The use of a slipclutch allows odd-sized
records to be played. The sample unit lowers the record slowly to the turntable. |
12" to 6" can be intermixed in any order in the stack.
No single record on turntable.
Sample is
VM 1555
protrusion on pickup arm
|
|
| Pickup Arm Scan on Separated Record |
The record carrier moves the record over the turntable. Then the pickup arm touches the separated record. The record then
drops to the turntable. If no record is found, automatic shutoff occurs. The use of a slipclutch allows odd-sized
records to be played. The sample unit keeps the unplayed and played records on separate shelves on the left. |
12" to 6" can be intermixed in any order in the stack.
No single record on turntable.
Sample is
Thorens TD-224
protrusion on pickup arm
|
|
| Feeler Wheels |
After the record drops, feeler wheels lower from the bottom of the arm. The arm then moves in and sets the wheels down
near the center of the record. Next, the wheels roll the arm toward the edge of the record. The wheels are canted and
vertically aligned to make the arm stop at the edge of the top record on the turntable. Then the wheels retract and the arm
plays the record. |
12" to 6" can be intermixed in any order in the stack.
Plays single record on turntable.
Sample is
Dual 1004
feeler wheels in pickup arm
|
|
| METHOD |
HOW IT WORKS |
RECORD ORDER REQUIRED |
SAMPLE CHANGER PHOTO |
| Record Underside Scan |
The arm moves toward the center of the turntable, and than rises to touch the stack. There are two special wheels on top
of the arm and a feeling edge. The pickup arm swings back and forth like a pendulum, moving farther out each time. If the
feeler touches the edge of the bottom record of the stack, the feeling stops. The arm swings out and the record drops. Then
the arm moves in to play the record. If no record is found, automatic shutoff occurs. The use of a slipclutch allows odd-sized
records to be played. |
12" to 6" can be intermixed in any order in the stack.
No single record on turntable.
Sample is
Miracord 9
bar with wheels on top of pickup arm
|
|
| Shelf Bottom Record Sensor |
The record shelf senses the size of the record while determining which pusher edge to use to push it off. |
12" & 10" can be intermixed in any order in the stack.
No single record on turntable.
Sample is
Webster 70
feeler is inside side shelf
|
|
| |
| GROUP |
METHOD |
HOW IT WORKS |
RECORD ORDER REQUIRED |
SAMPLE CHANGER PHOTO |
C
O
M
B
I
N
A
T
I
O
N
O
F
M
E
T
H
O
D
S |
Size Switch and Tilting Feeler |
The user selects the size range of the records by moving a control. A falling record feeler allows some intermix of record sizes. |
Usually 12" & 10" intermixed, with 7" played separately. Some mix 12" with the selected size.
No single record on turntable.
Sample is
Collaro Sentinel
slide switch on right, sensor by overarm base
|
|
| Speed-Size Switch and Droplever |
The user selects the size range of the records by moving the speed control. A falling record feeler allows some intermix
of record sizes.
The sample unit does 12" & 10" 78, 12" & 10" 33, 7" 33, 7" 45. |
Usually 12" & 10" intermixed, with 7" played separately. Some mix 12" with the selected size.
No single record on turntable.
Sample is
V-M 406
small knob, sensor on rear of tonearm
|
|
| Rising Feeler and Tilting Feeler |
The rising feeler (white arrow) determines whether a stack of 7" records, or larger records, is being played. A falling record feeler
(black arrow) allows intermix of 12" & 10" records. |
Usually 12" & 10" intermixed, with 7" played separately.
No single record on turntable.
Sample is
V-M 935
feelers at white and black arrows
|
|
| METHOD |
HOW IT WORKS |
RECORD ORDER REQUIRED |
SAMPLE CHANGER PHOTO |
| Droplever and Size Override Control |
The falling record feeler allows intermix of record sizes. The size override control allows play of a single record. |
Three sizes intermixed in any order.
Plays single record on turntable.
Sample is
Philips AG1003
left pushbutton, feeler protruding from slot.
|
|
C
O
M
B
I
N
A
T
I
O
N
O
F
M
E
T
H
O
D
S |
Semaphore and Swinging Feeler |
The combined feeler axle is vertical. The feelers move toward the spindle at the beginning of the cycle. Then the falling record
rotates the semaphore away from the spindle different amounts, or does not strike the feeler, for different record sizes. The feeler
retracts after the arm indexes.
When the single-play spindle is installed, the swinging feeler is raised to the height where it contacts, or does not
touch, a single record in the turntable. A roller contacts the record, so it is not damaged. When the multiple-play spindle is
installed, the swinging feeler drops below the level of the records, so it does not interfere with the semaphore. |
Three sizes can be intermixed in any order in the stack.
Plays single record on turntable.
Sample is
Dual 1008
curved objects left of arm base
|
|
| 3-Size Arm Scan and Size Override Control |
The pickup arm touches the stack before the record drops, then backs off so the record can drop. If no record weight is on the
spindle, automatic shutoff prevents the scan. The size override control sets the size for a single record on the turntable. |
Three sizes. Larger records must be below smaller records.
Plays single record on turntable.
Sample is
Miracord PW-161
protrusion on pickup arm, knob in group
|
|
| METHOD |
HOW IT WORKS |
RECORD ORDER REQUIRED |
SAMPLE CHANGER PHOTO |
| Semaphore and Index Arm |
The combined feeler axle is vertical. The feeler moves toward the spindle at the beginning of the cycle, contacting the largest
record on the spindle. A falling 12" record rotates the semaphore away from the spindle, selecting 12" operation. 10"
and 7" records do not push the feeler out enough to select a different size. If the feeler does not contact a record, automatic
shutoff occurs.
|
12" & 10" intermixed in any order, 7" must be last.***
No single record on turntable.
Sample is
Garrard RC 210
curved object over the tonearm
|
|
| Pickup Arm Scan and Index Arm |
The pickup arm touches the edge of the stack before the record drops, then backs off so the record can drop. If no record is found,
automatic shutoff occurs. The use of a slipclutch allows odd-sized records to be played.
The index arm performs the same feeling action at the same time, but is used for automatic speed change. It allows small
45 RPM records to be stacked above larger 33 RPM records.
|
12" to 6". Larger records must be below smaller records.
No single record on turntable.
Sample is
Collaro Conquest Custom
protrusion on pickup arm, index arm behind overarm
|
|
| |
*** This sensor has also been used to intermix record speeds in the stack (large 33 RPM with small 45).
**** This sensor has also been used to sense the record speed for the stack (large 33 RPM or small 45).
In the following discussion, the use of Audiotex record repeating discs is listed. The repeating discs are 2.75 inches (7 cm) in
diameter, with the standard 1.5 inch hole used for large-hole records. A spider adaptor can be inserted to make the repeating discs
work with small-hole records. Two repeating discs are shown at right:
When making up a record stack, place a repeating disc on top of the record that is to be played twice. When the repeating disc
drops, the changer will play the record under it again, if it can.
Note that they can not be used with the following kinds of changers:
- Changers that have the active record dropping parts in the side shelf. Repeat discs in the stack can break records.
- Changers with the nodding spindle dropping mechanism (Philco). Repeat discs in the stack can break records.
- Changers that change records by methods other than dropping or lowering them down a spindle (e.g. Thorens TD-224).
- Changers that measure the size of the record while it is separated from the other records.
- Changers that can't drop the discs (some need enough weight in the record to work the spindle).
The following is a table of properties of these methods. The column "REPEAT DISCS" tells how the repeating discs can or can not
be used with each type or record changer.
| PROPERTIES OF SIZE SENSING METHODS |
| |
| GROUP |
METHOD |
SIZE INTERMIX |
SINGLE RECORD PLAY |
REPEATING RECORDS |
REPEAT DISCS |
NO
SENSOR |
Size
Switch |
none |
Yes |
Yes* |
Yes** |
Speed and
Size Switch |
none |
Yes |
Yes* |
Yes** |
Record Shelf
Position |
none |
Yes |
Yes* |
Yes if pusher in spindle** |
Spindle
Selected Size |
none |
Yes |
Yes* |
DANGER - breaks records |
|
METHOD |
SIZE INTERMIX |
SINGLE RECORD PLAY |
REPEATING RECORDS |
REPEAT DISCS |
TURNTABLE
SENSOR |
Rising
Feelers |
none |
Yes |
Yes* |
Yes* |
Swinging
Feeler |
none |
Yes |
Yes* |
Yes** |
Hole Size
Feeler |
none |
Yes |
Yes* |
Yes** |
3-Size Turntable
Arm Scan |
none |
Yes |
Yes* |
Yes** |
|
METHOD |
SIZE INTERMIX |
SINGLE RECORD PLAY |
REPEATING RECORDS |
REPEAT DISCS |
DROP
SENSOR |
Droplever
|
2 or 3 sizes, random order |
Only smallest size |
Only smallest size* |
Only smallest size** |
Tilting
Feeler |
2 or 3 sizes, random order |
Only smallest size |
Only smallest size* |
Only smallest size** |
Semaphore
|
2 or 3 sizes, random order |
Only smallest size† |
Only smallest size* |
Only smallest size** |
|
METHOD |
SIZE INTERMIX |
SINGLE RECORD PLAY |
REPEATING RECORDS |
REPEAT DISCS |
STACK
SENSOR |
Index
Arm |
2 or 3 sizes, larger records must be below smaller records |
no |
no |
If next record
is same size** |
3-Size
Arm Scan |
3 sizes, larger records must be below smaller records |
no |
no |
If next record
is same size** |
Pickup
Arm Scan |
12" to 6", Larger records must be below smaller records |
no |
no |
If next record
is same size** |
|
METHOD |
SIZE INTERMIX |
SINGLE RECORD PLAY |
REPEATING RECORDS |
REPEAT DISCS |
SEPARATE
RECORD
SENSOR |
Pickup Arm Scan
on Lowered Record |
12" to 6", random order |
no |
no |
no |
Pickup Arm Scan
on Separated Record |
12" to 6", random order |
no |
no |
no |
Feeler
Wheels |
12" to 6", random order |
Yes |
Yes* |
Yes** |
Record
Underside Scan |
12" to 6", random order |
no |
no |
If next record
is same size** |
Shelf Bottom
Record Sensor |
2 sizes, random order |
no |
no |
DANGER - breaks records |
|
METHOD |
SIZE INTERMIX |
SINGLE RECORD PLAY |
REPEATING RECORDS |
REPEAT DISCS |
COMBINED
METHODS |
Size Switch and
Tilting Feeler |
12" & 10", random order |
10" & 7" |
10" & 7" * |
10" & 7" ** |
Speed-Size Switch
and Droplever |
12" & 10", random order |
10" & 7" |
10" & 7" * |
10" & 7" ** |
Rising Feeler and
Tilting Feeler |
12" & 10", random order |
10" & 7" |
10" & 7" * |
10" & 7" ** |
Droplever and
Size Override Control |
3 sizes, random order |
Yes |
If override control used* |
Size set on override control** |
Semaphore and
Swinging Feeler |
3 sizes, random order |
Yes |
Only 7" records* |
Only 7" records** |
3-Size Arm Scan and
Size Override Control |
3 sizes, Larger records must be below smaller records |
Yes |
If override control used* |
If next record
is same size** |
Semaphore and
Index Arm |
12" & 10" random order, 7" last |
No |
No |
10" & 7" ** |
Pickup Arm scan
and Index Arm |
12" to 6", Larger records must be below smaller records, 33 below 45 |
no |
no |
If next record
is same size** |
| |
* Provided that the record dropping and/or auto shutoff mechanisms can be persuaded to repeat records.
** Provided that the record dropping mechanism is capable of dropping the disc.
Do not use repeat discs with a record dropping mechanism that pushes the rim of the record. It could break the record on top of the disc.
The exact range of sizes provided depends on the design of the individual model.
| COMPANIES USING SIZE SENSING METHODS |
| |
| GROUP |
METHOD |
COMPANIES |
NO
SENSOR |
Size
Switch |
Many, including Admiral, BSR, Collaro, Dual, GE, Glenburn, Maestro, Magnavox, Miracord, Panasonic, Philips, RCA, Seeburg,
Technics, VM, Zenith |
Speed and
Size Switch |
Admiral, BIC, BSR, Dual, Garrard, Miracord, PE, Philips, RCA, Technics, VM |
Record Shelf
Position |
Many, including Admiral, Aero, Belmont, Bendix, Emerson, Markel, Milwaukee-Erwood, Motorola, Philco, Philips, RCA, Seeburg,
Webster, VM, Zenith |
Spindle
Selected Size |
Milwaukee-Erwood |
|
METHOD |
COMPANIES |
TURNTABLE
SENSOR |
Rising
Feelers |
Admiral, PE, Philco, Philips |
Swinging
Feeler |
Capehart, Philips |
Hole Size
Feeler |
Magnavox, Philips |
3-Size Turntable
Arm Scan |
Philips |
|
METHOD |
COMPANIES |
DROP
SENSOR |
Droplever
|
BSR, Collaro, Crescent, Lesa, Panasonic, Philips, RCA, Silvertone, Supraphon, Universal Camera |
Tilting
Feeler |
Balfour, Collaro, Farnsworth, GE, Glaser-Steers, Philips, Silvertone, VM, Webster, Zenith |
Semaphore
|
Garrard, PE, Silvertone, Webster |
|
METHOD |
COMPANIES |
STACK
SENSOR |
Index
Arm |
Garrard, Webster, Zenith |
3-Size
Arm Scan |
Collaro, Magnavox, Miracord, Philips |
Pickup
Arm Scan |
BSR, Collaro, Magnavox |
|
METHOD |
COMPANIES |
SEPARATE
RECORD
SENSOR |
Pickup Arm Scan
on Lowered Record |
PE, VM |
Pickup Arm Scan
on Separated Record |
Lincoln, Thorens |
Feeler
Wheels |
Dual, Luxor |
Record
Underside Scan |
Miracord |
Shelf Bottom
Record Sensor |
Aga, Dual, Garrard, Philips, Thorens, Webster |
|
METHOD |
COMPANIES |
COMBINED
METHODS |
Size Switch and
Tilting Feeler |
Collaro, Philips, Thorens |
Speed-Size Switch
and Droplever |
Miracord, Webster, VM |
Rising Feeler and
Tilting Feeler |
Admiral, BSR, RCA, Telefunken, VM |
Droplever and
Size Override Control |
Philips, Supraphon |
Semaphore and
Swinging Feeler |
Dual |
3-Size Arm Scan and
Size Override Control |
Miracord |
Semaphore and
Index Arm |
Garrard, Wumo |
Pickup Arm scan
and Index Arm |
Modified Collaro |
| |
