Series and Parallel SEPAR 409

The following circuit is a simple circuit that can be used for low voltage uses, and with care, line voltage uses. The page author built a version for photoflood lighting purposes. It does not keep the screw shells of lamps on the neutral side for safety in case bulbs are removed. The requirement of polarized plugs with the screw shell connected to the neutral blade makes this circuit technically illegal to use today for permanently-wired line-voltage circuits. But a simple provision makes it safer. And since it is built as a portable device, not building wiring, the National Electrical Code does not really apply.

The SEPAR circuit numbers used here have been used by the page author for years to catalog the various circuits.

The same circuit can be used for switching impedances and nonpolarized heating elements.

SEPAR 409

Wanting more functions, the page author first thought of modifying SEPAR 401 with a 4-position switch to give F, G, H, and open. The original position H was relabeled I to allow H to be used with F and G. The result was SEPAR 401A.

Then he wanted to actually switch photoflood lamps with it, since this change provided a function needed for this (not available in SEPAR 401). So he redesigned the circuit to use groups of wall switches that are commercially available.

He also moved switch C to the other terminal of lamp 2. This connects two screw shells to switch B (the other two screw shells already were connected to switch J). The result is SEPAR 409.

SEPAR 409 provides all series combinations and all parallel combinations.

SEPAR 409 provides two series of two lamps each, a setting needed by photographers.

All 56 possible output displays are shown, out of 4096 switch settings.*

Note that if only one switch in a group can be set to its letter position at any one time (setting more than one letter in a group is redundant), there are only 864 switch settings.

The four groups include:
switches D & E
switches F, G, & H
switches I & J
switches K & L

KEY TO TABLE ENTRIES

ON
- Connected directly to power

DIM
  - 2 or 3 lamps in series
  - series in a series-parallel
  - series in a parallel-series

Glim
- 4 or more lamps in series
- parallel in a series-parallel

glim
- Inner series in an (S - P - S)
(even dimmer than Glim)

off
- No current through lamp

−
- Switch position unimportant

(A) (letter in parentheses)
- Switch must be ON

(o) (o in parentheses)
- Switch must be off

*
- All possible displays shown.
- Redundant combos not shown.

†
- Former settings for photofloods

Letters indicate closed switches.

No letter for a switch, or an o for a switch, means the switch is open, or is in the unlabeled position.

Redundant combinations include connections to only one side of the line, shorted out lamps, and extra connections that no current flows through.

Magenta shading shows new combinations not possible with SEPAR 401.

Yellow shading shows better switch combinations than those on SEPAR 401.

In SEPAR 409, any time a lamp is at full brightness, the screw shell is always connected to neutral.

(S - P) is a series-parallel circuit (parallel inside series).

(P - S) is a parallel-series circuit (series inside parallel).

(S - P - S) is series-parallel-series.

(P - S - P) is parallel-series-parallel.

Panel Illustrations

' A	3 2	1 -	o o
B '	C o o	' -D	o '

Symbols for panel illustrations:

' Switch must be on.
o Switch must be off.
- (alone) not used.
1 (number) lamp on original unit.
A (letter) switch on original unit.
-A (letter) invert original switch.

Settings	1	2	3	4	Settings	1	2	3	4
SWITCH	LAMPS				SWITCH	LAMPS
o †	off	off	off	off	ACH †	DIM	DIM	off	off
AB	ON	off	off	off	AEJ	DIM	off	DIM	off
BCF	off	ON	off	off	AIL	DIM	off	off	DIM
DFJ	off	off	ON	off	CEFJ	off	DIM	DIM	off
JK	off	off	off	ON	BCGK	off	DIM	off	DIM
ABCF †	ON	ON	off	off	DFL	off	off	DIM	DIM
ABDFJ	ON	off	ON	off	ACDJ †	DIM	DIM	DIM	off
ABJK	ON	off	off	ON	ACGL	DIM	DIM	off	DIM
BCDFJ	off	ON	ON	off	AEL	DIM	off	DIM	DIM
BCFJK	off	ON	off	ON	BCDK	off	DIM	DIM	DIM
DFJK	off	off	ON	ON	ACDL †	Glim	Glim	Glim	Glim
ABCDFJ †	ON	ON	ON	off	(P-S)	-	-	-	-
ABCFJK	ON	ON	off	ON	ACHJK	DIM	DIM	off	ON
ABDFJK	ON	off	ON	ON	AEJK	DIM	off	DIM	ON
BCDFJK	off	ON	ON	ON	ABCGK	ON	DIM	off	DIM
ABCDFJK †	ON	ON	ON	ON	ABEK	ON	off	DIM	DIM
(S-P)	-	-	-	-	BCDFL	off	ON	DIM	DIM
ACEHJ	DIM	Glim	Glim	off	CEFJK	off	DIM	DIM	ON
ACHIL	DIM	Glim	off	Glim	ABCDFL	ON	ON	DIM	DIM
ADHIL	DIM	off	Glim	Glim	ACDJK	DIM	DIM	DIM	ON
ACHIK	Glim	DIM	off	Glim	ABCDK	ON	DIM	DIM	DIM
ACEFJ	Glim	Glim	DIM	off	ACDHK †	DIM	DIM	DIM	DIM
ADHIK	Glim	Glim	off	DIM	(P-S-P)	-	-	-	-
ACFIL	Glim	off	DIM	Glim	ACEFJK	Glim	Glim	DIM	ON
ADFIL	Glim	off	Glim	DIM	ACEHJK	DIM	Glim	Glim	ON
CDFIL	off	Glim	Glim	DIM	ABCEGK	ON	Glim	Glim	DIM
ACDHIL	DIM	Glim	Glim	Glim	(S-P-S)	-	-	-	-
ACEFL	Glim	Glim	DIM	DIM	ACEHL	DIM	Glim	glim	glim
ACEGL	DIM	Glim	Glim	DIM	ACEHK	Glim	DIM	glim	glim
ACDFIL	Glim	Glim	Glim	DIM	Special	-	-	-	-
ACDHIK †	DIM	DIM	DIM	DIM	BJ †	safety bulb change

SEPAR 409 constructed by the page author

P A	1 2	3 4	K L
B C	F G H	D E	I J

SEPAR 409 panel

A safety feature is included for changing light bulbs without disconnecting the cords. Turning ON switches B and J connects all of the screw shells and/or neutral polarized outlet slots to the neutral.

Turning P off, B on, and J on makes the system safe for changing bulbs.

If it is possible that the controls could be tampered while the user is changing a bulb, a key-operated switch could be put on switch P for added safety.

Percentages and Voltages for Identical Loads

Series-Parallel Combinations	Constant Resistance Loads												Variable Filament Resistance
	Voltage Percent			120 V Supply			Label			Filament Color			Voltage Percent			120 V Supply			Filament Color
	Lev 1	Lev 2	Lev 3	Lev 1	Lev 2	Lev 3	Lev 1	Lev 2	Lev 3	Lev 1	Lev 2	Lev 3	Lev 1	Lev 2	Lev 3	Lev 1	Lev 2	Lev 3	Lev 1	Lev 2	Lev 3
Any Parallel	100%	-	-	120V	-	-	ON	-	-				100%	-	-	120V	-	-
2 in Series	50	-	-	60	-	-	DIM	-	-				50	-	-	60	-	-
3 in Series	33.3	-	-	40	-	-	DIM	-	-				33.3	-	-	40	-	-
4 in Series	25	-	-	30	-	-	Glim	-	-				25	-	-	30	-	-
Any in Parallel with 2 in Series	100	50	-	120	60	-	ON	DIM	-				100	50	-	120	60	-
2 Parallel sets of 2 in Series	50	-	-	60	-	-	DIM	-	-				50	-	-	60	-	-
2 Series sets of 2 in Parallel	50	-	-	60	-	-	DIM	-	-				50	-	-	60	-	-
1 in Series with 2 in Parallel	66.7	33.3	-	80	40	-	DIM	Glim	-				86	14	-	104	16	-
1 in Series with 3 in Parallel	75	25	-	90	30	-	DIM	Glim	-				96	4	-	115	5	-
2 in Series with 2 in Parallel	40	20	-	48	24	-	DIM	Glim	-				47.5	5	-	57	6	-
1 in Ser w/ 1 in Par w/ 2 in Ser	60	40	20	72	48	24	DIM	Glim	glim				83.3	16.7	8.33	100	20	10

The nonlinearity of filament resistance with current (heat) causes some of the series-parallel combinations to not display the expected filament brightness. This is because the lamps drawing lower current have a resistance as low as 1/10 of the resistances of the lamps drawing high current. The right three columns of the table show this effect.

Complete table of SEPAR 409 switch positions.

OTHER CIRCUITS SEPAR 409 CAN EMULATE

SEPAR 301

As on SEPAR 301

SWITCH			LAMP
A	B C	D	1	2	3
o	o	o	off	off	off	†
o	o	D	ON	off	off
o	B	o	DIM	DIM	off	†
o	B	D	ON	off	off
o	C	o	off	off	off	†
o	C	D	ON	ON	off	†
A	o	o	DIM	DIM	DIM	†
A	o	D	ON	off	off
A	B	o	DIM	DIM	off	†
A	B	D	ON	off	off
A	C	o	off	off	ON
A	C	D	ON	ON	ON	†

12 switch positions.

Note that hot and neutral are reversed in this emulation.

Items in parentheses must have the setting given.

SEPAR 301 on
SEPAR 409 panel

' '	1 2	3 -	o o
D '	C o B	' o	o A

SEPAR		switch
301	409	ON	off
-	A	(A)	-
D	B	brt	dim
-	C	(C)	-
-	D	(D)	-
-	E	-	(o)
C	F	brt	3
-	G	-	(o)
B	H	2	3
-	I	-	(o)
A	J	3	2
-	K	-	(o)
-	L	-	(o)
1	1
2	2
3	3
-	4

As on SEPAR 409

SWITCH			LAMP
B	F H	J	1	2	3
o	o	o	off	off	off	†
o	o	J	ON	off	off
o	F	o	DIM	DIM	off	†
o	F	J	ON	off	off
o	H	o	off	off	off	†
o	H	J	ON	ON	off	†
B	o	o	DIM	DIM	DIM	†
B	o	J	ON	off	off
B	F	o	DIM	DIM	off	†
B	F	J	ON	off	off
B	H	o	off	off	ON
B	H	J	ON	ON	ON	†

SEPAR 302

As on SEPAR 302

SWITCH				LAMP
A	B	C	D	1	2	3
o	−	o	−	off	off	off	†
o	o	C	o	DIM	DIM	off	†
o	o	C	D	ON	off	off
o	B	C	o	off	ON	off
o	B	C	D	ON	ON	off	†
A	o	o	o	DIM	off	DIM
A	o	o	D	DIM	DIM	DIM	†
A	B	o	o	off	off	ON
A	B	o	D	off	off	ON
A	o	C	o	DIM	glim	glim
A	o	C	D	ON	off	off
A	B	C	o	off	ON	ON
A	B	C	D	ON	ON	ON	†

16 switch positions.

Lamps 1 and 3 traded.

Switch E works backwards.

SEPAR 302 on
SEPAR 409 panel

' A	3 2	1 -	o o
B '	C o o	' -D	o '

SEPAR		switch
302	409	ON	off
A	A	3	2
B	B	brt	dim
-	C	(C)	-
-	D	(D)	-
-D	E	2	brt
C	F	brt	3
-	G	-	(o)
-	H	-	(o)
-	I	-	(o)
-	J	(J)	-
-	K	-	(o)
-	L	-	(o)
3	1
2	2
1	3
-	4

As on SEPAR 409

SWITCH				LAMP
A	B	F	-E	3	2	1
o	−	o	−	off	off	off	†
o	o	F	E	DIM	DIM	off	†
o	o	F	o	ON	off	off
o	B	F	E	off	ON	off
o	B	F	o	ON	ON	off	†
A	o	o	E	DIM	off	DIM
A	o	o	o	DIM	DIM	DIM	†
A	B	o	E	off	off	ON
A	B	o	o	off	off	ON
A	o	F	E	DIM	glim	glim
A	o	F	o	ON	off	off
A	B	F	E	off	ON	ON
A	B	F	o	ON	ON	ON	†

SEPAR 305

As on SEPAR 305

SWITCH				LAMP
A	B	C	D	1	2	3
−	o	−	o	off	off	off	†
o	o	o	D	off	off	off
o	o	C	D	ON	off	off
o	B	o	o	DIM	DIM	off	†
o	B	o	D	off	off	off
o	B	C	o	off	ON	off
o	B	C	D	ON	ON	off	†
A	o	o	D	DIM	DIM	DIM	†
A	o	C	D	ON	off	off
A	B	o	o	DIM	DIM	ON
A	B	o	D	off	off	ON
A	B	C	o	off	ON	ON
A	B	C	D	ON	ON	ON	†

16 switch settings.

Lamps 1 - 4 reversed.

Switch L works backwards.

SEPAR 305 on
SEPAR 409 panel

' o	- 3	2 1	' -D
A '	B o o	' o	o C

SEPAR		switch
305	409	ON	off
-	A	-	(o)
A	B	3	2
-	C	(C)	-
-	D	(D)	-
-	E	-	(o)
B	F	brt	3
-	G	-	(o)
-	H	-	(o)
-	I	-	(o)
C	J	brt	dim
-	K	(K)	-
-D	L	2	brt
-	1
3	2
2	3
1	4

As on SEPAR 409

SWITCH				LAMP
B	F	J	-L	4	3	2
−	o	−	L	off	off	off	†
o	o	o	L	off	off	off
o	o	J	o	ON	off	off
o	F	o	L	DIM	DIM	off	†
o	F	o	o	off	off	off
o	F	J	L	off	ON	off
o	F	J	o	ON	ON	off	†
B	o	o	o	DIM	DIM	DIM	†
B	o	J	o	ON	off	off
B	F	o	L	DIM	DIM	ON
B	F	o	o	off	off	ON
B	F	J	L	off	ON	ON
B	F	J	o	ON	ON	ON	†

SEPAR 401

As on SEPAR 401

Settings	1	2	3	4	Settings	1	2	3	4
SWITCH	LAMPS				SWITCH	LAMPS
o †	off	off	off	off	ACGJ †	DIM	DIM	off	off
AB	ON	off	off	off	AEJ	DIM	off	DIM	off
BCF	off	ON	off	off	AHL	DIM	off	off	DIM
DFJ	off	off	ON	off	CEFJ	off	DIM	DIM	off
JK	off	off	off	ON	CFHL	off	DIM	off	DIM
ABCF †	ON	ON	off	off	DFL	off	off	DIM	DIM
ABDFJ	ON	off	ON	off	ACDJ †	DIM	DIM	DIM	off
ABJK	ON	off	off	ON	ACGL	DIM	DIM	off	DIM
BCDFJ	off	ON	ON	off	AEL	DIM	off	DIM	DIM
BCFJK	off	ON	off	ON	BCDK	off	DIM	DIM	DIM
DFJK	off	off	ON	ON	ACDL †	Glim	Glim	Glim	Glim
ABCDFJ †	ON	ON	ON	off	(P-S)	-	-	-	-
ABCFJK	ON	ON	off	ON	ACGJK	DIM	DIM	off	ON
ABDFJK	ON	off	ON	ON	AEJK	DIM	off	DIM	ON
BCDFJK	off	ON	ON	ON	ABCGK	ON	DIM	off	DIM
ABCDFJK †	ON	ON	ON	ON	ABEK	ON	off	DIM	DIM
(S-P)	-	-	-	-	BCDFL	off	ON	DIM	DIM
ACEGJ	DIM	Glim	Glim	off	CEFJK	off	DIM	DIM	ON
ACEFJ	Glim	Glim	DIM	off	ABCDFL	ON	ON	DIM	DIM
ACFHL	Glim	Glim	off	DIM	ACDJK	DIM	DIM	DIM	ON
ADFHL	Glim	off	Glim	DIM	ABCDK	ON	DIM	DIM	DIM
CDFHL	off	Glim	Glim	DIM	(P-S-P)	-	-	-	-
ACEFL	Glim	Glim	DIM	DIM	ACEFJK	Glim	Glim	DIM	ON
ACEGL	DIM	Glim	Glim	DIM	ACEGJK	DIM	Glim	Glim	ON
ACDFHL	Glim	Glim	Glim	DIM	ABCEGK	ON	Glim	Glim	DIM

648 switch combinations.

47 useful nonredundant positions listed here.

' A	1 2	3 4	K L
B C	F G o	D E	H J

SEPAR 401 on
SEPAR 409 panel

SEPAR		switch
401	409	ON	off
A	A	A	o
B	B	B	o
C	C	C	o
D	D	D	o
E	E	E	o
F	F	F	o
G	G	G	o
-	H	-	(o)
H	I	H	o
J	J	J	o
K	K	K	o
L	L	L	o
1	1
2	2
3	3
4	4

Items in parentheses must have the setting given.

As on SEPAR 409

Settings	1	2	3	4	Settings	1	2	3	4
SWITCH	LAMPS				SWITCH	LAMPS
o †	off	off	off	off	ACGJ †	DIM	DIM	off	off
AB	ON	off	off	off	AEJ	DIM	off	DIM	off
BCF	off	ON	off	off	AIL	DIM	off	off	DIM
DFJ	off	off	ON	off	CEFJ	off	DIM	DIM	off
JK	off	off	off	ON	CFIL	off	DIM	off	DIM
ABCF †	ON	ON	off	off	DFL	off	off	DIM	DIM
ABDFJ	ON	off	ON	off	ACDJ †	DIM	DIM	DIM	off
ABJK	ON	off	off	ON	ACGL	DIM	DIM	off	DIM
BCDFJ	off	ON	ON	off	AEL	DIM	off	DIM	DIM
BCFJK	off	ON	off	ON	BCDK	off	DIM	DIM	DIM
DFJK	off	off	ON	ON	ACDL †	Glim	Glim	Glim	Glim
ABCDFJ †	ON	ON	ON	off	(P-S)	-	-	-	-
ABCFJK	ON	ON	off	ON	ACGJK	DIM	DIM	off	ON
ABDFJK	ON	off	ON	ON	AEJK	DIM	off	DIM	ON
BCDFJK	off	ON	ON	ON	ABCGK	ON	DIM	off	DIM
ABCDFJK †	ON	ON	ON	ON	ABEK	ON	off	DIM	DIM
(S-P)	-	-	-	-	BCDFL	off	ON	DIM	DIM
ACEGJ	DIM	Glim	Glim	off	CEFJK	off	DIM	DIM	ON
ACEFJ	Glim	Glim	DIM	off	ABCDFL	ON	ON	DIM	DIM
ACFIL	Glim	Glim	off	DIM	ACDJK	DIM	DIM	DIM	ON
ADFIL	Glim	off	Glim	DIM	ABCDK	ON	DIM	DIM	DIM
CDFIL	off	Glim	Glim	DIM	(P-S-P)	-	-	-	-
ACEFL	Glim	Glim	DIM	DIM	ACEFJK	Glim	Glim	DIM	ON
ACEGL	DIM	Glim	Glim	DIM	ACEGJK	DIM	Glim	Glim	ON
ACDFIL	Glim	Glim	Glim	DIM	ABCEGK	ON	Glim	Glim	DIM

Ignore switch H.

Use switch I for 401 switch H.

SEPAR 409 IN DEPTH

Complete table of SEPAR 409 switch positions

Simple switching selection between series and parallel

SEPAR 409
SERIES OR PARALLEL OPERATION
OF LAMPS AND IMPEDANCES

Simple Light Bulb Circuit

SEPAR 409 SERIES OR PARALLEL OPERATION OF LAMPS AND IMPEDANCES

Simple Light Bulb Circuit

SEPAR 409
SERIES OR PARALLEL OPERATION
OF LAMPS AND IMPEDANCES