March 2019:

In future DRL will be concentrating on sales and support of the DVR2 regulators, generally suited to motorcycle use. We intend to continue sales and support of our well proven DVR3 and DVR4 products for six months or more, in order not to let down our customers with a bump.

Read more about the change in this post on our 'blog' site.

DVR4™ Regulator - Bosch style field

electronic dynamo regulator & cut-out: current limited, field to live ('series')



Plus UK, European or Rest of World postage RoW includes Australasia, Americas, Africa & India!

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Current Limit Option
Voltage Option
Select EARTH Polarity

Description and features of the DVR4™

The DVR4™ is a high output, current limited electronic dynamo regulator / cut-out to suit dynamos fitted to many classic cars and other vehicles. Current outputs in 4 steps of 8, 11, 16 or 22 Amps (310 Watts) are available to suit 6 or 12 V systems. The DVR4™ controls Continental dynamos where the 'live' end of the field winding connects to the output (61/D+) and the other end of the field connects to the control unit, DF terminal. (Sometimes inaccurately described as 'series' field.) The field winding resistance must be greater than 2.5 ohms. An example are the Bosch units used on classic Volkswagens and many other makes. Also for use on BMW and other motorcycles, including the Kawaski W1 & W2 'Weezas'.

Available in Negative and Positive Earth connection. The positive earth configuration suits many American cars with Type A generators.

This is a modern electronic 'solid state' replacement for the original electromechanical two bobbin 'CVC' regulator units and 3 bobbin type with separate current regulation fitted in Classic Vehicles equipped with dynamo direct current electrical generation. The DVR4 features improved performance over 'relay' types giving excellent charge voltage stability from the lowest revs to maximum speed, and zero low speed battery discharge into the dynamo. The DVR4 is electrically and mechanically robust, housed in a strong aluminium housing for good heat transfer.

DVR4 size is 60 x 42 x 18 mm. The unit produces only a modest degree of heat but proper mounting is recommended to limit temperature rise and extend its life. It is supplied with an adhesive thermal bonding pad on the top surface, for attaching to a flat (not hot) metal surface to act as a heat-sink. Alternatively a small finned heat-sink is available for the 22 Amp product to achieve enhanced air cooling. A pair of vertical holes, with 54 mm centre spacing, M3 clearance (3.2 mm diameter) allow a pair of screws as an alternative (or additional) means to secure the regulator. Connections are by flying leads of approximately 110 mm. Bared wire ends allow the customer to connect using their preferred method.

Compare our 'DVR' regulators with other products on the market: they exhibit no battery discharge back to the dynamo at low revs. By employing MOSFET transistors in the cut-out function the DVR3 & 4 generate far lower heat output than other units using ordinary diodes to perform the cut-out. The battery charging voltage is always stable (above cut in speed) regardless of your speed. Furthermore your dynamo will start up (and be regulated) with no or very low battery charge.

View DVR4 data sheet (Adobe Acrobat PDF format)

The DVR4™ may also be employed as the regulator/cut-out with Siba or Bosch Dynastarts (with a separate starter solenoid if required). In its 12 V, 8 Amp from the it performs exactly the same functions as the discontinued DVR2-D, just a different shape package. The DVR2-D data-sheet may help with connecting the DVR4 in the Dynastart application.

View DVR2-D data sheet (Adobe Acrobat PDF format)


We also stock a small range of useful accessories to accompany your new Regulator!

View our range of Voltage Regulators