sbm20_counter's Introduction

SBM20 Counter

With this PCB and an SBM20 tube you can build a small, battery operated geiger counter. It can be supplied by two AA batteries, for example. Depending on the battery type you can populate the Step-Up (<5V) or the Step-Down (>5V). The left part of the PCB generates the approx. 400V for the tube, the right part amplifies and shapes the pulses for the LED and buzzer. The buzzer is optional if the LED is sufficient feedback.

Acknowledgements

The circuit is bodged together from multiple sources on the internet, mainly from MightyOhm.

Contact

Send Questions to @[email protected]

BOM

Qty	Value	Footprint	Parts	DIGIKEY	LCSC
1	Red	CHIPLED_1206	LED
1	100R	R-TRIMM3224J	R14
1	1M	R-EU_R1206	R2
2	1N4148	SOD123	D2, D3
2	1k	R-EU_R0603	R13, R32
1	1k5	R-EU_R0603	R1
2	1n	C-EUC0603	C3, C6
1	1u	C-EUC1206	C9
1	2u2	C-EUC1206	C10A
1	4M7	R-EU_R1206	R10
1	4k7	R-EU_R0603	R9
1	10mH	L-EUL8065	L1
2	10n 630V	C-EUC1206	C1, C5
4	10u	C-EUC1206	C8, C8A, C8B, C10
1	20p	C-EUC0603	C11
1	22R	R-EU_R0603	R5
1	27k	R-EU_R0603	R4
1	30R	R-EU_R0603	R5A
3	100k	R-EU_R0603	R7, R11, R12
2	100n	C-EUC0603	C2, C7
1	120k	R-EU_R0603	R16
1	180k	R-EU_R0603	R6
1	220k	R-EU_R0603	R3
1	220p	C-EUC0603	C4
1	330R	R-EU_R0603	R8
1	680k	R-EU_R0603	R15
1	CMMR1U-06	DO-214AC	D1	1514-CMMR1U-06TRPBFREECT-ND
1	DN350T05	SOT23	T1	DN350T05DICT-ND
1	LM555D	LM555D	IC2	LM555CMX/NOPBCT-ND
1	LM556D	LM556D	IC1	2156-LM556CM-FS-ND
2	MMBT3904	SOT23	T2, T3	4530-MMBT3904CT-ND
2	SBM20	FUSECLIP	SBM20	F3781-ND
1	XC914X	SOT23-5	IC3	893-1373-1-ND
1	XC926X	SOT23-5	IC3A	893-1330-1-ND
2	4u7	L5050	L2, L2A	490-7779-1-ND
1	KJL-5020	BUZZER-5020	BEEP		C556937
1	AO3404A	SOT23	T6		C30010
1		SWITCH-SPDT-SMD-A	PWR		C319019