Maplin derivative 75WRMS lateral mosfet amp.

[vilfort]

For those who would like more detail, here is an article: Mosfet Amplifier (EMM Jun 81)

Sure enough, the old Hitachi circuit. A Paul Kemble web page - Hitachi Fet designs. Used in Hitachi amps of the era and also in Perreaux from the mid 80's. Sounds great with a tube pre-amp.

D.

 

[nigelwright7557]

Thanks for that link I have pdf'ed it for future reference.

I built my first one in 1980.

 

[nigelwright7557]

Current circuit diagram with improvements from original circuit.

 

[nigelwright7557]

Parts list BOM.

C:\pcbcad720\MAPLINLATMOSFETASORG_4.pls

Reference Value Symbol name
--------- ----- -----------

D 1 * 1N4004
Q 2 ? ALF08N16K
Q 8 * ALF08N16V_L2
Q 7 ? ALF08P16K
Q 9 * ALF08P16V_2
IC 1 B++ CONN1
IC 2 OUTPUT CONN1
IC 3 INPUT+ CONN1
IC 4 GND CONN1
IC 5 B-- CONN1
IC 6 GND CONN1
C 1 100nf C_P2
C 2 6N8 100V C_P2
C 3 100UF 63V C_P2_ELECT
C 4 100NF 250V C_P2
C 5 100pf 100V C_P2
C 6 100pf 100V C_P2
C 7 100pf 63V C_P2
C 8 100UF 63V C_P2_ELECT
C 9 47uf 63v C_P2_ELECT
C 10 100NF C_P2
C 11 10UF 63V C_P2_ELECT
PIN 1 ? HOLE4MM
PIN 2 ? HOLE4MM
PIN 3 ? HOLE4MM
PIN 4 ? HOLE4MM
Q 5 MPSA42
Q 6 MPSA42
Q 1 MPSA92
Q 3 MPSA92
Q 4 MPSA92
R 9 1K PRESET_RS161-9911_416M
R 10 1K PRESET_RS161-9911_416M
R 1 100R R
R 2 100R R
R 3 47R R
R 4 10R 3W R_4W
R 5 12K R
R 6 100R R
R 7 47K R
R 8 390R R
R 11 2K2 R
R 12 33K R
R 13 47K R
R 14 1K R
R 15 220R R
R 16 100R R
R 17 3k9 R
R 18 3k9 R
R 19 100R R

 

[nigelwright7557]

In the link below is to a Maplin lateral mosfet story.
I fixed the noise problems with RC decoupling the front end on my pcb.
Maplin Mosfet amplifier finally noise free! - YouTube

 

[nigelwright7557]

I also added footprints for TO247 and TO3.
Only one or the other can be used and not both at same time.

 

[nigelwright7557]

Open to offers on last two modules.
PM me.
p+p is £4.99 UK, £14.99 Europe. £17.99 rest of world.

 

[bravi]

PCB for Maplin circuit

Hi
Nigel, I will take the remaining two boards if available.

Pl let me know your paypal address for payment

Cheers!

Ravi

 

[nigelwright7557]

PM sent
Regards Nigel

 

[nigelwright7557]

A couple of pcb's left unpopulated.
And 2 pcb's fully built and tested.