ResonantLive Sound Archive

Equipment file · Telephone transmitter

Loose-contact transmitter

Emile Berliner · 1877

Evidence status · documented

Identity and core specifications are documented; some historical fields remain unavailable.

Emile Berliner filed a caveat on 14 April 1877 for a transmitter that varied the pressure, and so the resistance, at a contact between a vibrating plate and a fixed point. His patent was not granted until 1891 (US 463,569) after long Patent Office proceedings. Combined with Francis Blake's design, it became the Berliner–Blake transmitter used by Bell licensees in the 1880s.

Introduced
1877
Category
Telephone transmitter
Intended use
Converting speech into current through a loose contact between diaphragm and electrode
Production
Made in small numbers for the Bell companies after 1878; superseded by the Berliner–Blake transmitter

Equipment photographs · 1

US patent 463,569 (1891): loose-contact telephone transmitter

1 / 1 · US patent 463,569 (1891): loose-contact telephone transmitter

US patent 463,569 (1891): loose-contact telephone transmitter·Emile Berliner·Public domain (US patent)

Why it mattered

  1. 01

    Variable contact pressure gave far louder, clearer transmission than Bell's original transmitters.

  2. 02

    Its principle, refined with carbon by Blake, Edison and Hunnings, became the basis of the carbon microphones that fed early public-address amplifiers.

Engineering record

Operating principle
A metal diaphragm pressed lightly against a fixed contact; sound-pressure changes at the contact varied the circuit's resistance and current[1]
Patent history
Caveat 14 April 1877, application 4 June 1877, patent granted 17 November 1891 (US 463,569)[2]

Original pricing

No reliable period price located

2026 equivalent

Not calculated without a reliable original price.

Public price evidence was not sufficient to publish a defensible original figure.

Use in the field

Combined with Francis Blake's design to form the Berliner–Blake transmitter, adopted for Bell telephone service in the 1880s[3]

Manuals & original documents

Sources

  1. 1US222652 — Improvement in Electrical Contact TelephonesUS Patent Office (via vieuxtelephone.com) · patent · 1879
  2. 2US463569 — Combined Telegraph and TelephoneUS Patent Office (via telecom.wiki) · patent · 1891
  3. 3Blake Transmitter, Page 3: Berliner and Blaketelephonecollecting.org · reference

Contribute to the record

Know more about Loose-contact transmitter?

Corrections, firsthand information, original documents, and credited photograph sources are welcome.

Your email is private and will not appear in the archive. Contributions are not published automatically.

Back to all equipment Back to Origins of electrical sound

Help build the archive

A missing piece? A correction?

Contribute to Resonant

Support the archive

Resonant is built one verified record at a time: research hours, archival image rights, and the hosting that keeps every era, equipment file, and citation free to read. If this archive is useful to you, a donation of any size keeps the next entry moving.

How donations are used
Venmo@mercer-aplinOpen Venmo, tap the pay field, type the handle, then send any amount.Send any amount · no account needed to viewCash App$MercerAplinOpen Cash App, tap the $cashtag field, type the tag, then send any amount.Send any amount · no account needed to view

Payments go directly to the archive’s editor through Venmo and Cash App. Resonant is an independent project rather than a registered charity, so donations are not tax-deductible and nothing is sold or subscribed to in return.