Build document for
Frequency central
Routemaster
Power supply / bus board
Routemaster is a simple to build combined power supply and busboard.
It can be powered from a 12VAC wallwart, or alternatively a 12VAC centre-tapped
transformer.
Options are included for Euro. MOTM, or Dotcom power headers.
The supply us adjustable for +/-12V or +/-15V using multi-turn trimmers
There is an onboard 5V supply too.
IMPORTANT
6 pin MTA-156 silk screen is the wrong way around on Rev2 PCBs. If in doubt, use a DMM to check
orientation.
Bill of materials - Including links to parts stocked by Tayda
2 x 220R
1 x 330R
4 x 1K
All resistors ¼ watt
metal film
2 x 100nF 100V poly box
2 x 10uF 35V elecyrolylic
3 x 100uF 35V elecyrolylic
6 x 4700uF 25V elecyrolylic
1 x LM317
1 x LM337
1 x 78L05
8 x 1n4004
3 x 5mm LED
2 x 2K trimmer
2 x heatsink
Power headers
Build guide - It’s best to populate the PCB in height order, smallest first.
1. Install and solder all resistors.
2. Install and solder all 1n4004 diodes.
3. Install and solder 100nF capacitors.
4. Install and solder all three LEDs. Follow the diagram on the PCB to ensure correct polarity.
5. Install and solder 78L05. This part is not indicated on the PCB, it’s right next to the +15/12V
LED. Ensure correct polarity.
6. Install and solder 10uF and 100uF capacitors. Ensure correct polarity.
7. Install and solder 2K multi-turn trimmers.
8. Install all power headers.
9. Bolt LM317 and LM337 to their heatsinks, install and solder. I find it best to solder the
middle pin first, which ensures against solder bridges.
