An 1808 capacitor at 250 V or below has no Walsin part in the same case: the 1808 ladder starts at 500 V. For a United Kingdom signalling buyer, 232 of the 317 Walsin 1808 part numbers have a 1206, 1210 or 1812 twin on four electrical fields. The body changes, and 13 lines are stocked.
Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the Walsin Technology (Walsin) MLCC parametric export: 24,026 rows, 23,601 distinct part numbers, in 16 series. This post is for a procurement or design engineer at a United Kingdom rail electronics maker, or a repairer holding legacy boards, who has an 1808 multilayer ceramic capacitor to cross. Every part number below is real and every count is ours. Where it states a development, it names the source, the document date and the day we fetched it, 23 October 2026.
What did Network Rail publish about digital signalling in March 2026?
A plan for years three to five of its seven-year control period. Network Rail’s delivery plan for digital signalling in Control Period 7, a year-three update dated March 2026, says the period runs from 1 April 2024 to 31 March 2029 and that Funding Period 1, 2029 to 2034, is when many schemes are due to commission. It also records that the Northern City Line became, in May 2025, the first commuter mainline in Britain to run on digital signalling with no lineside signals.
The plan cuts the European Train Control System total from about 1.5 billion pounds in its March 2024 plan to about 1 billion pounds. It says nothing about capacitors, component supply or any named supplier, and we draw no conclusion about which parts any UK rail company buys. We have no relationship with Network Rail.
| Point | What the source says | Source date | Match / mismatch |
|---|---|---|---|
| Period | Control Period 7 runs 1 April 2024 to 31 March 2029 | Network Rail, March 2026 | Match for context only |
| What follows | Funding Period 1, 2029 to 2034, is when many schemes are due to commission | Network Rail, March 2026 | Mismatch with any component claim: no part or volume is named |
| First mover | Northern City Line on digital signalling with no lineside signals, May 2025 | Network Rail, March 2026 | Mismatch: nothing on electronics supply |
| Funding | European Train Control System total about 1.5 billion pounds falling to about 1 billion pounds | Network Rail, March 2026 | Mismatch: nothing on passives |
Where does the Walsin 1808 voltage ladder start?
At 500 V. We measured every Walsin MLCC row in the 1808 case: 420 rows, 393 distinct part numbers. Take out the 59 safety-series rows, whose “rated voltage” is an impulse figure of 5,000 or 6,000 V, and the 24 soft termination rows, and the 317 distinct part numbers in the general purpose and middle-to-high-voltage series have no member below 500 V. The series is titled 200 V to 4 kV, and it has 0 parts at 200 or 250 V in the 1808 case, against 440 rows at 0805 and 378 at 1206.
| Rated voltage | Distinct 1808 part numbers | Stocked lines | Match / mismatch for a legacy 250 V line |
|---|---|---|---|
| 500 V | 26 | 0 | Mismatch: the first rung, 250 V above the line |
| 630 V | 26 | 1 | Mismatch: same direction |
| 1,000 V | 69 | 5 | Mismatch: a different class of part |
| 1,500 V | 4 | 0 | Mismatch |
| 2,000 V | 60 | 2 | Mismatch |
| 2,500 V | 5 | 0 | Mismatch |
| 3,000 V | 117 | 5 | Mismatch |
| 4,000 V | 10 | 0 | Mismatch |
| 200 V and 250 V | 0 | 0 | No matching row in the 1808 case |
Stocked lines are those of our Hong Kong list, as at 23 September 2026. One row, 1808B102M252, carries the series title, a tab character and 1808 in its size cell, so a filter on a size of exactly 1808 misses it; we counted it. Twenty rows repeat a part number already counted, which is why 337 rows are 317 part numbers. We have not seen the 1808 floor counted anywhere.
How many 1808 part numbers have a twin in another case?
232 of 317. We matched each 1808 part number to a part in 1206, 1210 or 1812 with the same dielectric, capacitance, tolerance and rated voltage, in the same two series. 171 have a 1812 twin, 157 a 1206 twin and 123 a 1210 twin; 85 have none. 44 of the 232 have a twin that is on our list.
The 85 without are mostly at the top of the ladder: 56 are C0G (written NPO in the export) at 3,000 V and 14 are X7R at 3,000 V. If your 1808 line is a high-voltage line, the case is the constraint, and the answer is often that no Walsin part exists in a case that fits.
The bodies differ, and the export says by how much. Walsin’s own length and width columns give the 1808 as 4.50 by 2.03 mm, the 1812 as 4.50 by 3.20 mm, the 1210 as 3.20 by 2.50 mm and the 1206 as 3.20 by 1.60 mm. TDK’s published part-numbering page gives the same family of sizes, 4520 as 4.50 by 2.00 mm and 4532 as 4.50 by 3.20 mm, so the gap is not a Walsin quirk. A 1812 keeps the length and adds 1.17 mm of width; a 1206 or 1210 shortens the part by 1.3 mm. None is a drop-in on the land pattern. Our post on case sizes, imperial and metric shows why the four digits mislead.
Which worked part numbers show the twins, and what differs?
Four stocked 1808 lines, and one with no twin. The last column is for your incumbent part.
| Walsin part | Dielectric, value, tolerance, voltage | Body L by W, thickness | Match / mismatch | Your incumbent |
|---|---|---|---|---|
1808B152K102 |
X7R, 1500 pF, 10%, 1,000 V | 4.50 by 2.03 mm, 1.25 mm | Reference line, stocked as at 23 September 2026 | |
1210B152K102 |
X7R, 1500 pF, 10%, 1,000 V | 3.20 by 2.50 mm, 1.25 mm | Match on dielectric, value, tolerance, voltage, thickness; mismatch on case and footprint; stocked | |
1812B152K102 |
X7R, 1500 pF, 10%, 1,000 V | 4.50 by 3.20 mm, 1.25 mm | Match on the same five; mismatch on width; not stocked | |
1808N471J102 |
C0G, 470 pF, 5%, 1,000 V | 4.50 by 2.03 mm, 2.00 mm | Reference line, stocked | |
1210N471J102 |
C0G, 470 pF, 5%, 1,000 V | 3.20 by 2.50 mm, 1.60 mm | Match on dielectric, value, tolerance, voltage; mismatch on case and thickness; stocked | |
1808B152K302 |
X7R, 1500 pF, 10%, 3,000 V | 4.50 by 2.03 mm, 2.00 mm | Reference line, stocked | |
1812B152K302 |
X7R, 1500 pF, 10%, 3,000 V | 4.50 by 3.20 mm, 2.00 mm | Match on dielectric, value, tolerance, voltage, thickness; mismatch on width; stocked | |
1808N301J302 |
C0G, 300 pF, 5%, 3,000 V | 4.50 by 2.03 mm, 2.00 mm | Reference line, stocked; no matching row at 1206, 1210 or 1812 |
Thickness is exported as text and its tolerance differs by part, so read it from the row, not the nominal. Our post on soft termination and board bend explains why a longer body and a wider body bend differently, and rail boards see vibration that a bench does not.
What will we not tell you about the United Kingdom?
Anything about UK rail standards, approvals, customs or product conformity. We hold no office, entity or stock in the United Kingdom; our locations are Hong Kong, Shenzhen, Singapore and Jiangmen, with Chengdu in preparation. We state no duty, border procedure, transit time or carrier, and we give no legal or customs advice; confirm with your compliance team. We make no claim that any Walsin part is approved for railway use.
How can Venatech help a United Kingdom rail electronics buyer?
We start with the cross-reference. Paste your 1808 line into the free cross-reference tool, which decodes 18 manufacturers’ part numbers across 800,000+ crossable parts and lists Walsin candidates with match and mismatch fields, or upload a list to the BOM checker, up to 500 part numbers. The Hong Kong ready-stock list is a dated snapshot, 23 September 2026, never live-synced. Walsin is the only line we are authorised for; Stackpole and Viking are lines we supply. We work from Hong Kong, in small lots, and you can request a quote through the site.
A worked example from our own export: a 1,500 pF, 10 percent, X7R, 1,000 V line in 1808 maps to 1808B152K102, stocked; if the board will take a different body, 1210B152K102 shares its value and thickness. Our MLCC range lists the families. We hold neither ISO 9001 nor IATF 16949. Qualification stays with you.
The short version
For an 1808 capacitor, check the voltage before the case. Walsin lists nothing in 1808 below 500 V, so a 250 V line has no same-case part, and the ladder runs 500 V to 4,000 V across 317 part numbers. 232 of the 317 have a 1206, 1210 or 1812 twin on four electrical fields, 171 of them at 1812 and 123 at 1210, and the body changes by up to 1.3 mm in length or 1.17 mm in width.
Send us one 1808 capacitor from a signalling board and we will return the Walsin parts with the differences stated. If your land pattern cannot move, will a 1812 at the same length do?
Sources
Fetched 23 October 2026. The development statements above come from these pages; the part data comes from our own Walsin export and stock list.
- TDK, MLCC part numbering description, case size code table, © 2025: https://product.tdk.com/en/products/common/pdf/mlcc_partnumber_description.pdf
- Network Rail, “Our delivery plan for Digital Signalling, Control Period 7: Year three update”, dated March 2026: https://www.networkrail.co.uk/wp-content/uploads/2026/07/Our-Delivery-Plan-for-digital-signalling-in-CP7-Year-3-update.pdf
Frequently asked questions
Does Walsin make an 1808 capacitor at 250 V?
Not in the export. The 317 distinct 1808 part numbers in the general purpose and middle-to-high-voltage series start at 500 V, 26 of them, and run to 4,000 V. The 0805 and 1206 cases carry 440 and 378 rows at 200 or 250 V. A 250 V line moves case or goes up to 500 V.
How many Walsin 1808 capacitors have a twin in another case?
232 of 317 have a part with the same dielectric, capacitance, tolerance and voltage at 1206, 1210 or 1812: 171 at 1812, 157 at 1206 and 123 at 1210. 85 have none, 56 of them C0G at 3,000 V. A twin is a catalogue match on four fields, not a footprint match.
Is a 1812 twin a drop-in for an 1808?
No. Walsin’s export gives the 1808 as 4.50 by 2.03 mm and the 1812 as 4.50 by 3.20 mm. The length is shared and the width grows by 1.17 mm. A 1206 or 1210 is 1.3 mm shorter. Check the land pattern and board bend before you commit.
Why do you exclude the safety series from the 1808 count?
Their “rated voltage” in the export is an impulse figure of 5,000 or 6,000 V, not a working voltage. Counting them would put 59 rows at a voltage the parts do not work at. They are 59 of 420 rows in the case. We exclude them from every voltage statement here.
Did Network Rail say anything about capacitors?
No. The March 2026 digital signalling plan covers funding, schemes and fleet fitment, and is silent on components. It says Funding Period 1, 2029 to 2034, is when many schemes are due to commission. We draw no conclusion about which parts any UK company buys.
Do you state UK rail approvals or customs rules?
No. We hold no UK entity or stock and no Walsin document that states a railway qualification. We give no legal or customs advice; confirm with your compliance team. We supply parts, and qualification stays with you.