website/content/museum/heathkit-ec-1.md

---
title: HEATHKIT EC-1
categories:
- Computers
types:
- Professional Computer
origins:
- U.S.A.
years:
- '1960'
params:
  name: EC-1
  image: /media/museum/photos/heathkit_ec1_system_1.jpg
  company: /companies/heathkit
  company_name: HEATHKIT
  specs:
  - label: NAME
    value: EC-1
  - label: MANUFACTURER
    value: Heathkit
  - label: TYPE
    value: Professional Computer
  - label: ORIGIN
    value: U.S.A.
  - label: YEAR
    value: '1960'
  - label: KEYBOARD
    value: Potentiometers and switches
  - label: CPU
    value: No processor but nine DC operational amplifiers
  - label: SPEED
    value: 0.5 to 15 repetitive operations per second
  - label: RAM
    value: No memory
  - label: TEXT MODES
    value: Volt-meter
  - label: SIZE / WEIGHT
    value: 50,2 (W) x 38,1 (H) x 29,2 (D) cm. / 21 Kg.
  - label: POWER SUPPLY
    value: Built-in 100 Watts main power supply
  - label: PRICE
    value: $400
  tabs:
  - photos
  - adverts
  photos:
  - title: EC-1 SYSTEM
    subtitle: ''
    text: ''
    image: /media/museum/photos/heathkit_ec1_1.jpg
  - title: FRONT PANEL
    subtitle: ''
    text: Each operational amplifier connectors are located with a small triangle.
    image: /media/museum/photos/heathkit_ec1_frontpanel_1.jpg
  - title: FRONT PANEL
    subtitle: ''
    text: ''
    image: /media/museum/photos/heathkit_ec1_front-panel_1.jpg
  - title: FRONT PANEL CLOSE-UP
    subtitle: ''
    text: ''
    image: /media/museum/photos/heathkit_ec1_frontpanel_2.jpg
  - title: TOP SIDE
    subtitle: ''
    text: When the system overheated, user opened the trap door for insuring a better ventilation.
    image: /media/museum/photos/heathkit_ec1_topview_1.jpg
  - title: TOP - INSIDE
    subtitle: ''
    text: ''
    image: /media/museum/photos/heathkit_ec1_top.jpg
  - title: INSIDE
    subtitle: ''
    text: Notice the nine operational amplifier vacuum tubes along the front panel.
    image: /media/museum/photos/heathkit_ec1_inside_1.jpg
  - title: INSIDE
    subtitle: ''
    text: ''
    image: /media/museum/photos/heathkit_ec1_inside.jpg
  - title: DETAILS
    subtitle: ''
    text: Seven of the nine operational amplifier vacuum tubes placed along the front panel.
    image: /media/museum/photos/heathkit_ec1_tubes.jpg
  - title: IN USE...
    subtitle: ''
    text: ''
    image: /media/museum/photos/heathkit_ec1_inuse_1.jpg
  - title: IN USE
    subtitle: ''
    text: ''
    image: /media/museum/photos/heathkit_ec1_in-use.jpg
  - title: ASSEMBLY MANUAL COVER
    subtitle: ''
    text: ''
    image: /media/museum/photos/heathkit_ec1_manual_1.jpg
  - title: OPERATIONAL MANUAL
    subtitle: ''
    text: ''
    image: /media/museum/photos/heathkit_ec1_manual_2.jpg
  adverts:
  - title: HEATH CATALOG
    subtitle: ''
    text: Extract from the 1961 Heathkit catalog
    image: /media/museum/pubs/heathkit_ec1_catalogextr_1.jpg
  comments:
  - author: wahl (germany)
    date: Monday 4th June 2018
    text: ic this ec-1-operational and komplte?cabels,tubes etc,,,,,,,,,,,fred
  - author: Franco Savio (Vinovo (Torino) - Italy)
    date: Friday 9th May 2003
    text: |-
      I'm an italian electronic engineer, I'm interested in vacuum tube analog operational amplifiers.\
      I will be very gratefull to people that could send me schematics of EC-1 and other vacuum tube operational amps.\
      Thank you and best regards.\
      Franco savio - E-mail: francosavio1@tin.it
  oc_id: 787
  source:
    url: https://web.archive.org/web/20220819210536/http://www.old-computers.com/museum/computer.asp?c=787
    date: '2022-08-19'
---

From 1950 to 1965, electronic analogue vacuum-tube computers were used to design, test and run civilian and military equipment like aircraft, ships or rockets. The first systems were very expensive. However, components cost (especially vacuum tubes) was steadily decreasing.

In 1960, Heath Company launched the Heathkit EC-1, the first analogue computer (almost) anyone could afford. It was sold in kit or pre-assembled forms and was quickly and widely used in industry and universities.

Unlike our modern binary computers which accept only two values as entry (0 or 1), an analogue computer represents input and output data's in voltage levels. So, any positive or negative value could be read directly from the built-in meter. An external oscilloscope could be also used as a display device, as well as a grapher for printed results.

In spite of its apparent simplicity, the EC-1 could solve a multitude of complex mechanical and mathematical problems thanks to nine DC operational amplifiers, three initial condition power supplies, potentiometers, relay contacts, high precision resistors and capacitors, and a built-in oscillator for repetitive operation (from 0.1 to 15 operations per second).

The computer was described by Heathkit as "*Excellent teaching aid for a course in computer electronics - Vividly illustrates the electronic analogies to mathematical problems - Handles problems as complex as fluid flow, damped harmonic motion, and flight of a projectile in a viscous medium*"

Computer problems could be 'programmed' by inserting several patch cords into the problem-board sockets and thus linking in chain several built-in components together.

The EC-1 and other analogue computers were used until 1965, when first affordable digital computers became available.

Here is some EC-1 unusual technical features taken from the Heathkit brochure:\
**Amplifiers**: Open loop gain approximately 1000. Output -60 +60 volts at .7 ma.\
**Power supplies**: ± 300 volts at 25 ma electronically regulated; variable from +250 to +350 volts\
**Repetitive operation**: Multivibrator cycles a relay at adjustable rates (.1 to 15 cps)