The Alternative Comparison Lamp Controller
The WYFFOS Alternative Comparison Lamp Controller has been designed to
switch a mains supply to three 13 amp. outlets controlled from a software
interface equivalent to that found on the ISIS and UES comparison lamp
controllers. From a software point of view the operation of a comparison
lamp controller appears the same irrespective of which type of controller
is being used with WYFFOS. The main purpose of the Alternative Controller
is to provide a switching control point for comparison lamps which cannot
be accommodated within the ISIS controller format Therefore any comparison
lamp with its own mains driven power supply can be connected to an outlet
and switched on or off from the either the Engineers, or Users interfaces.
1.1 Document history:
Version 0.1 draft, not for issue. Dec. 1994
Version 1.0 First release. Feb 1995
1.2 Version notes:
V0.1 Engineering draft copy not for issue.
V1.0 First release of the official copy
1.3 Mnemonics used throughout the text:
WYFFOS Wide field Fibre Optic Spectrograph.
ISIS Double beam spectrograph at Cassegrain.
UES Utrecht Echelle spectrograph at Nasmyth
The enclosure is a 2U 19" distribution panel which is fitted with 3 x 13
amp outlet sockets., plus a fuse and blanking panel all as BS1363 faceplates.
Within the enclosure is a quad output solid-state relay and some circuitry
to provide a status output for each mains outlet.
3. Circuit description:
The main switching component is based around a quad output solid state
relay which can be switched from an input voltage range of between 4 -
15v dc. Three of the relays are each connected to a 13A outlet socket.
The fourth is used to enable the other three from the control input line
on pin 25 on the 25W D connector. The neutrals are not switched and are
commoned to the incoming mains.
3.2 Status outputs:
Status outputs are available on the 25D connector at TTL level which are
derived from an AC/DC to logic interface opto-coupler connected to each
13A outlet. These devices have been configured to switch at a 230Vac threshold
level and not be influenced by the off state voltage and current produced
by the solid state relay. The 20K 6W resistor provides a minimum load to
the relay should nothing be connected to the 13amp. socket. The relay off-state
voltage is 38Vac. A low pass filter using the pull-up resistor 4K7 and
47f capacitor network ensures a constant logic level output from the opto-coupler.
This signal is inverted and buffered (SN7416) to the output connector.
The final logic level `1' indicates comparison lamp mains on. Logic level
`0' indicates comparison lamp off. Unused status outputs are held `lo'
as their off state, and linked connections 09 - 10 or 22 - 23 are used
for the connection status loop.
4. Parts lists:
Component Manufacturer Supplier & No. Cost per
& part number order code off item
2U x 19" empty RS 1 28.00
distribution panel 817-612
Single gang 13A MEM 3002 RS 3 02.90
Fused connection MEM 3210 RS 1 05.93
Blanking plate 1 MEM 3503 RS 1 01.20
Solid-state relay, Crydom Farnell 1 48.00
quad output TD24200 178-761
AC to logic Hewlett Farnell 3 02.77
interface Ic Packard HCPL3700
Buffer Hex inverting Texas RS 1 00.92
o/c Ic 7416 306-364
Resistor 4k7 0.25W RS 3 00.032
Resistor 91K 0.5W RS 3 00.052
Resistor 240 0.25W RS 1 00.032
Resistor 20k 6W RS 3 00.74
Vitreous enamel. 159-578
Electrolytic RS 3 00.126
capacitor 47uf 10v 103-941
Decoupling cap. from stock 2
0.1uF disc ceramic 15V
`D' connector 25W RS 1 03.75
plug solder (fixed) 466-191
6A mains cable from stock 2m
Mains cable RS 1 02.03
Reference data sheet HCPL-3700 RS
for logic interface ic. F10029
Reference data sheet TD24200 Farnell
for solid state relay
5. Circuit diagram:
This is where a circuit diagram will be hopfully... Hmmm you must be bloody
Original Document alt_man.doc by H. M. Stevenson RGO Cambridge
Converted to HTML by M. A. Parr firstname.lastname@example.org