CED 4001-16 Mains Pulser

The CED 4001-16 Mains Pulser generates mains-frequency-locked pulses that can be used to reduce the magnitude of mains pickup (‘hum’) in recorded signals. The output is on a BNC connector, double-isolated from mains and consists of a train of 150 microsecond positive-going 5V TTL pulses, suitable for direct connection to a 1401 Event input.

The Mains Pulser will run off any mains supply between 100 -240 V AC, 50 - 60 Hz. The case is earthed to mains earth. Current consumption is less than 100 mA.

Box size: 104mm x 126mm x 53mm (W x D x H).

How to use the Mains Pulser

The recommended method of use is to record the pulses on an Event channel, alongside the waveform signal. Hum removal can then be done off-line, for example by using the Spike2 scripts HumRemove or HumRemoveExpress. Averaging with respect to the mains-generated pulses gives a good copy of the hum component, which can be subtracted from the polluted signal to provide a cleaner version. Click on the video tutorial on the right for a demonstration.


Click to view video

This video tutorial shows you how to remove mains hum with the HumRemoveExpress.s2s script and a 4001-16 Mains pulser


Mains ‘hum’ is often complex and composed of odd harmonics of the mains frequency, making it very difficult to remove or suppress using simple high pass or notch filters. HumRemoveExpress.s2s is a Spike2 version 7 script that you can use offline to strip out much of this residual mains interference, making your data much more presentable and easier to analyse. This video tutorial shows how to use the script to remove mains hum.

Cambridge Electronic Design Limited

Registered in England: 972132

Registered office:

  • Cambridge Electronic Design Limited,
  • Technical Centre,
  • 139 Cambridge Road,
  • Milton,
  • Cambridge CB24 6AZ

VAT: GB 214 2617 96

Producer Registration number: WEE/BD0050TZ

Terms and Conditions of Sale

For our US customers, we can provide tax form W-8BEN, that identifies us as a UK company.

DUNS: 219151016
NAICS: 423490
Commodity codes
Hardware: 84716070
Software: 85234945

By email:


By post:
  • Cambridge Electronic Design Limited,
  • Technical Centre,
  • 139 Cambridge Road,
  • Milton,
  • Cambridge CB24 6AZ
By telephone:

(Int.+44) (0)1223 420186

From North America (Toll Free):

1 800 345 7794


Privacy policy

CED, through this site, does two things that relate to privacy. We would like to explain them.

Emails from down-loads

We offer free down-loads of many files on our site, from test programs to complete install files for updated versions of major packages like Spike2 and Signal.

When customers wish to take a down-load of a major package, we ask a few questions, including their name, email address, the serial number of the software for which they seek an upgrade and whether they would like an automatic email whenever we update the product. This information is emailed back to CED when they access the final down-load screen. Within this email, your browser transmits the type and version of browser you are using, and the screen resolution you are running.

The reasons why we take and keep this information are that it is useful for our software development team to know who has taken the latest versions, and it is useful for our web site development team to know which browsers people are using to view our site, and what resolution they have their screens set to.


When people down-load a major package, we try to write a cookie, a small file in your computer, that records your name, serial number of the software package, and the version you are down-loading. These files have a lifetime of one year.

The reasons for storing this information are firstly that if you ask for another down-load some other time, your details are read from the cookie and are pre-written into the form, to save you looking them up again. The other reason is that next time you access our site, your browser looks through your CED cookies and compares the versions down-loaded with the latest version numbers read from our site. If there is a later version of a product you have already down-loaded, we tell you on the home page screen, so you know that it is worth going to the down-load page again.

None of this information is ever given to anyone outside CED. ×