HardLabs

B 250 test

eshazen·scope-clock·hardware/b_250_test/b_250_test.kicad_pcb

B 250 test PCB layout, top view — open source AVR/Arduino board by eshazen

About the B 250 test PCB

B 250 test is an open source AVR/Arduino PCB design by eshazen, published on GitHub. It is a 2-layer board measuring 177.8 × 114.3 mm, with 45 components from 39 distinct parts.

Its main chip is the 6SN7, from the AVR/Arduino family. By type, the board carries 15 resistors, 13 capacitors, 6 connectors, 3 ICs, 2 diodes and 1 crystal.

From the project

ATTiny84a MCU SN76489 PSG 6T9 amp inspired by this design. Voltage doubler power supply

ATTiny84a MCU SN76489 PSG 6T9 amp inspired by this design. Voltage doubler power supply

The output stage is based at about 30mA B+. Hopefully the voltage doubler and extra winding on on the Antek can handle this OK.

Planning to use OT8SE+HF+5K transformer I have lying around from MPS. It's rated at 45mA DC.

Layout ~ done. Many parts have DigiKey "TR" option, need to fix this.

Main components on the B 250 test

6SN7

B 250 test bill of materials (BOM)

45 components, 39 distinct parts — part numbers from the project's BOM.

QtyPartRefs
1
6SN7
6T9
U1
1
6SN7
SN76489
U2
1
6SN7
ATtiny84A-P
U3
1
CXO_DIP8
X1
1
CONN_01X02
Conn_01x02
J1
1
CONN_01X04
Conn_01x02
J2
1
CONN_01X03
Conn_01x02
J3
1
CONN_01X06
AVR-ISP-6
J4
1
Conn_01x04
J5
1
Conn_01x02
J6
1
JP2
JP1
1
Speaker
LS1
1
25K
100k_audio
RV1
1
SW_SPST
SW1
1
AES_PT-31
T1
2
1N4007
D1, D2
2
100u 400V
C1, C2
2
0.025UF
100u 400V
C3, C4
3
0.1uF
C5, C11, C12
1
100uF 16V
C6
Show 19 more
QtyPartRefs
1
220PF
10uF 450V
C7
1
220PF
0.22uF 400V
C8
1
0.1UF
330pF 100V
C9
1
0.1UF
0.22uF 400V
C10
1
2.2uF
C13
1
120 ohm 5W
R1
2
200 ohm 5W
R2, R3
1
47k 2W
R4
1
1
R5
1
1K
R6
1
270 1W
R7
1
2.2K
R8
1
120K
R9
1
47k
R10
1
470K
R11
1
33K
R12
1
1.8K
270k
R13
1
1.8K
10k
R14
1
330
R15

B 250 test design files

The KiCad project lives in the eshazen/scope-clock repository on GitHub; these links point at the commit this page was built from.

B 250 test: common questions

What microcontroller does the B 250 test use?

The B 250 test is built around the 6SN7, from the AVR/Arduino family.

How big is the B 250 test PCB?

The B 250 test measures 177.8 × 114.3 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the B 250 test?

45 components, from 39 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the B 250 test design files?

From the eshazen/scope-clock repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.

Can I use the B 250 test design in my own project?

The repository has no license, so all rights stay with eshazen. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the B 250 test without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug AVR/Arduino firmware against it before you order a PCB.

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