Lamington III – components

Design  |  Construction  |  Components

Components for your Lamington III are readily available. All of the parts with the exception of the output valves are readily available from Australian suppliers Jaycar, Altronics and WES Components.

Be open to the possibility of scrounging resistors, capacitors from old TV sets, VCR’s etc. If you can get your hands on such an old piece of gear, you will probably find most of the smaller electronics parts for your amp. Where possible, check any salvaged resistor for correct value before using it in your amp.

Transformers

Transformers are available from Altronics, WES Components and Jaycar. The power supply transformers, M6672L (30V 1A)  and the M2154 (18V 1A) are readily available from the above suppliers. The M1130 output transformer is available from Altronics and WES Components.

Valves

My recommendation is to purchase your valves from Ebay. You can regularly see 6CM5/EL36  valves for sale from Australian sellers and you can also find Soviet equivalents 6P31S from overseas sellers quite cheaply. Beware of the Soviet 6P13S valve advertised as a 6CM5 equivalent – it is similar but not the same pinout. 12AX7s can be purchased from Altronics and Jaycar and you can also find them on ebay from Australian and overseas sellers.

I highly recommend that you download data for your chosen valves from the Web – just do a Google search for data for your valve type. Read the data in detail – it will give you not only pinout data for your valve, but also a heap of further info that will help you understand valves better.

For further info on valves you can download an electronic version of any issue of the ARRL Amateur Radio Handbook, or the Radiotron Designer’s Handbook. These are invaluable resources for the valve enthusiast.

Power Supply Capacitors

The main power supply capacitors C1-4) can be sourced from Ebay or Altronics – Altronics have 470uf 400V capacitors available.

However a much cheaper (free) option is available however.

Do the rounds of your local computer repair shops, and ask for any faulty/dead computer power supplies that they may have lying around. The older AT and ATX supplies each contain a couple of these 200V capacitors. Some later supplies only contain one 400V capacitor, but that could still be useable if you can find a similar supply with a similar value capacitor.  You need two pairs of the capacitors for your amp, so any value from 220uf to 560uf is fine as long as you have a pair of the same value for C1 and C2 and another pair for C3 and C4. These computer capacitors are ideal as they have very low internal resistance, and are designed for high current – they are ideal for your amp. These salvaged capacitors are what I used for the prototype and work really well.

Other Components

See the parts list below which will assist you in gathering the components for your amp. Fortunately, there are several sources available for each component, so you should have no problems locating the parts that you need.

Amplifier Parts list

C1 22uf16v
C2 22nf630v
C3 22nf630v
C4 1nf100v
C5 5n6100v
C6 100p100v
C7 1nf100v
C8 10nf100v
C9 100nf100v
C10 47nf630v
C11 47nf630v
R1 1M
R2 47K
R3 100K
R4 2K2
R5 100K
R6 2K2
R7 220K
R8 27K
R9 220k
R10 100K
R11 1M
R12 100K
R13 470
R14 1M
R15 10K
R16 4K7
R17 470K
R18 470K
R19 47K
R20 10K
R21 10K
R22 1
R23 1
R24 100 1W
R25 100 1W
RV1 1MA
RV2 1MB
RV3 1MB
T1 M1130
V1 12AX7
V2 12AX7
V3 6CM5/EL36
V4 6CM5/EL36

Power Supply Parts list

C1 470uf100v
C2 470uf100v
C3 470uf200v
C4 470uf200v
C5 47uf63v
C6 22uf400v
C7 22uf400v
C8 220nf250VAC
D1 1N5404
D2 1N5404
D3 1N5404
D4 1N5404
D5 1N4004
F1 1A
MainsSwitch
R1 470K1/2W
R2 470K1/2W
R4 10K1W
R5 10K1W
R6 47K1/2W
RV1 100K trimpot
T1 M6672 transformer
T2 M6672 transformer
T3 M2154 transformer