Davey 1-valver History I have trawled through every month’s edition of the Boy’s Own Paper from 1945 to its end in 1967, as well as its offshoot publications, and most of Gilbert Davey’s books.   It emerged that the Davey beginner's one-valver design appeared in several forms over a period of no less than thirty years.   The history of this extraordinarily long-lived design is well worth tracing.

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The various versions of the beginner's one-valver are described below in order of publication.   In later years, the sequence of versions can be confusing, because new editions of Davey's books appeared in interspersed fashion.   Rights issues may have prompted some of the build variations, and also small variations in the circuit diagram.   It helps if one keeps in mind that the main practical reason for revising the design for each edition was the changing availability of components, especially valves and coils.   The successive revisions follow the trend from reliance on home-made coils after the war, through plentiful choice of manufactured coils in the 50s and early 60s, and back to home-made ones in the late 60s and 70s. The thumbnail pictorial views on this page have been drawn from the build descriptions.   These views are intended merely to sum up the build arrangement, and are not working drawings.   Some components' shapes are conjectural.   For the Studio ‘E’ version, the layout accords with my conclusions as set out on the PLANNING MY STUDIO ‘E’ REBUILD page.     1948:.     Solid base; HL2K valve; home-made coil. 1948: Boy's Own Paper As far as I can find, the first version of Gilbert Davey's one-valver was that published in the February 1948 edition of Boy's Own Paper.   "Build a crystal or one-valve radio set" described first a crystal design on a simple solid baseboard chassis and front panel which had enough room to add the valve and associated components.   A home-made coil was described, having aerial and tuner windings, as well as an unused reaction winding ready for conversion to the one-valver.   The reaction capacitor was put in place for use as an optional aerial trimmer. The one-valve upgrade featured a 2-volt HL2K or similar triode in a surface-mounted valveholder, with its associated components all above the baseboard. The author reported that using a 25-foot aerial at his home a few miles from the nearest BBC transmitter, the prototype one-valver had received the 1947 Test Match broadcasts with sufficient strength to drive a small loudspeaker.

The circuit of the 1948 one-valver,     with component values.

Only the practical layouts were given, with no "theoretical" circuits.   From the information in the article I have drawn the theoretical circuit as shown, for comparison with the later pentode circuit (see below).   The circuit was designed around the components the young constructor was likely to be able to obtain in the immediate post-war period. It is worth noting that unlike many one-valve circuits of the period, no HF choke was specified - just a 10kΩ resistor in series with the phones.   Tuning and reaction capacitors were both specified as .0005μF. (1) The following November's edition gave details for adding a second valve.   For an interesting variation on the 1948 triode version using a later Davey coil, see YOUR OTHER DAVEY SETS page.

1957:     Raised baseboard; DAF91 valve;     Teletron D/R coil.

1957: Fun with Radio, 1st edition After the 1948 version as above, I have been unable to find a subsequent appearance of the Davey one-valver in the Boy's Own Paper backnumbers, or its offshoot publications, until 1961 (see later).   However, the design must have been revised as below some time before 1957, and may have appeared as a separate BOP supplement which interested readers could send for.   If you can confirm the existence of such a supplement, I would be grateful if you would CONTACT ME. Be that as it may, the "Beginner's One-Valve Set" included (with other popular BOP designs) in Gilbert Davey's first book, Fun with Radio, published in October 1957, is clearly descended from the 1948 design. The circuit was revised to use a 1.4 volt pentode (DAF91) of the type which became readily available chiefly for use in portable radios.   The B7G valveholder required a through hole mounting, so a simple solid baseboard would not do.   A wood chassis in the form of an inverted tray was suggested, with the front panel fixed to one edge. (2)

The one-valver circuit and     components list from     Fun with Radio, 1st edition, 1957.     Drawn by R Barnard Way; reproduced     with acknowledgments to R Lawrence.     Other rights may subsist.     Image from site author's copy.

Using these miniature valves meant that a 2-volt accumulator was no longer needed, and dry-cell batteries could be used for both HT and LT.   These valves incorporated a screen grid, so appropriate components were added (R3 and C4 in this diagram). By the mid-50s, several firms were producing ready-made coils suitable for simple receivers, and instead of a home-made coil, the Teletron D/R coil was specified.   This had aerial, grid (medium wave) and reaction windings.

1957:     The Studio ‘E’ one-valver     according to the BBC leaflet.

1957: The Studio ‘E’ set With the Studio ‘E’ leaflet to hand, we can re-assess its place in the sequence of Davey one-valvers.   I have re-drawn my thumbnail view to accord with the leaflet. The theoretical circuit is the same as that which appeared in Fun with Radio, first edition, with the same coil (Teletron D/R), and variable capacitors (.0005μF/500pF tuning; .0001μF/100pF reaction).   Fixed capacitors are the same, but R2 and R3 (anode and screen grid resistors) are lowered somewhat, perhaps to ensure adequate reaction with the 69 volts HT supplied by the specified combined HT/LT battery.   For the valve, DAF91 or DAF96 are given as alternatives. (3) I previously speculated that the split-floor chassis idea had been adapted for the Studio ‘E’ from the short-wave receiver that appears on page 59 of Fun with Radio, first edition.   This feature would have contributed towards ease of construction for the many first-time builders who followed the Studio ‘E’ series. Now that the leaflet is to hand, this guess is still more tempting, as it can be seen that the component layouts of the two sets are strikingly similar.   Both designs mount the valve dead centre on the slot, and both place the coil to its left as seen from the front.   The tuning and reaction capacitors are disposed the same way - tuning on the left, reaction on the right (again as seen from the front).   Finally, the aerial, earth and phones terminals occupy the same positions across the back of the chassis.   However, the different valve and coil types used in each set mean that the point-to-point wiring differs quite a lot between the two. A simple medium-wave TRF set like the Beginner's One-valver is quite uncritical in layout.   It seems likely that Gilbert Davey simply reproduced both the slotted chassis and component arrangement from the short-wave set, then "joined the dots" to suit the components of the Studio ‘E’ set.   But why leave so much space at one side?   Was it so as to leave romm for adding a second valve and associated components, as indeed I did to my first set? 1959 - 1961: Fun with Radio, 2nd and 3rd editions I have not been able to inspect the second (1959) and third (1961) editions of Fun with Radio (they are missing from the British Library collection), but Doug Brown has kindly confirmed by enquiry that the third edition carries the beginner's one-valver chapter exactly as it appeared in the first (1957) edition - see above. (4)   We may thus be sure that the same version was included in the second edition.

1962: Boy's Own Companion No.4    Metal-chassis one-valver     with home-made coil; title picture.     Copyright © Lutterworth Press;     reproduced by kind permission.     British Library image; Copyright ©     British Library Board: Shelfmark 12841.gg.23.

1961: Boy's Own Paper The June 1961 BOP carried a most elegant one-valver version, built into a metal chassis with flanges tall enough for the front flange to house all the controls and thus serve as the front panel. A home-made coil (with aerial winding, medium- and long-wave tuning windings, and reaction winding), together with the valve, were displayed proudly on the top face of the chassis.   The valve was specified as 1T4 or DF91, with the layout showing pin connections to suit. There was a variation from the usual arrangement in that the voltage to the screen grid was via a resistor from the anode side of the phones, rather than from HT+ve.   This article was reprinted in the 1962 Boy’s Own Companion No.4. (5)   In both publications, the circuit diagram showed the reaction coil and capacitor below the ground line, possibly to ring the changes for rights reasons.

1962:     Baseboard on side runners, DF91 or     DF96 valve, Teletron D/R coil.

1962: Fun with Electronics, 1st edition A chassis arrangement owing something to the Studio ‘E’ build was adopted for Fun with Electronics (1962).   The baseboard was shown supported on side runners (but is not split transversely), and paired sockets were shown at the rear of the baseboard.   The valve was specified as DF91 or DF96, and the Teletron D/R coil was used again.   The layout placed the tuning capacitor on the same side as the coil (left side), and the reaction capacitor on the valve's side.   An on-off switch was included in the LT+ve supply. (6) The circuit diagram was re-drawn for Fun with Electronics, possibly again for rights reasons.   Some lines are dog-legged, and the reaction circuit is shown leading to ground between the aerial and grid coils.   The screen grid components repeated the arrangement used in the metal-chassis 1961 design (above).

1965-69:     Revised to use Repanco coil,     and wavechange switch.

1965-69: Fun with Radio, 4th & 5th editions By the fourth edition (1965), the Teletron coil had evidently become hard to buy, as we find the practical layout altered to show the Repanco DRR2 coil (the theoretical circuit diagram was unaltered since the first edition and still showed the connections for the Teletron coil).   The Repanco coil had medium and long-wave windings (necessitating a wavechange switch) and a reaction winding, but no aerial winding. The fifth edition of Fun with Radio (1969) repeated this version exactly. (7)

1972:     Home-made coil re-introduced as     commercial supplies dwindled.

1972: Fun with Electronics, 2nd edition By 1972, manufacturers were moving away from coils suitable for simple sets, and the Teletron D/R coil was out of production. The Fun with Electronics chapter was revised to give the choice of either the Repanco DRR2 coil (wavechange switch required), or a home-made coil with aerial, grid (medium-wave) and reaction windings, as shown in the thumbnail.   The on-off switch was still shown, so sets built to this design might have had one or two switches on the front panel, depending on the coil used. (8)

1978:     With the home-made long-     and medium-wave coil.

1978: Fun with Radio, 6th edition By 1978 (Fun with Radio, 6th edition), the Repanco coil was still available and was still shown in the one-valver layout.   The book's theoretical circuit was finally updated to show the Repanco coil as well.   A refinement was added to the circuit in the form of a .001μF capacitor across the headphone terminals, presumably as a tone-control element. The trend away from manufacture of coils for simple sets continued, and this edition therefore included a chapter on home-made coils.   Details were given of the dual-waveband home-made coil originally published in the June 1961 BOP. (9) The chassis build shown was as in previous Fun with Radio editions.   My thumbnail drawing shows this chassis with the home-made coil. It would have been necessary to place the valve well to one side of the chassis in order to accommodate this large-diameter coil.

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As far as I know, the sixth edition of Fun with Radio was the last to be published in the UK.   Editions often seen identified as published in 1986 in the USA by Sportshelf & Soccer Associates appear to be UK editions imported for sale there. (1) Boy’s Own Paper, Lutterworth Periodicals, February 1948, pp18-20. (2) Fun with Radio, Gilbert Davey, Edmund Ward Ltd, 1957, pp16-18. (3) Making Your Own Radio Set, BBC, September 1957 (the Studio ‘E’ leaflet). (4) Fun with Radio, Gilbert Davey, 3rd edition, Edmund Ward Ltd, 1961, pp19-21;       details forwarded by Doug Brown, May 2011. (5) Boy’s Own Paper, Lutterworth Periodicals, June 1961, p61;       reprinted in Boy’s Own Companion, Vol 4, Lutterworth Press, 1962, p100. (6) Fun with Electronics, Gilbert Davey, Edmund Ward Ltd, 1962, pp13-17. (7) Fun with Radio, Gilbert Davey, 4th edition, Edmund Ward Ltd, 1965, pp14-16,       and 5th edition, Kaye & Ward Ltd, 1969, pp16-18. (8) Fun with Electronics, Gilbert Davey, 2nd edition, Kaye & Ward Ltd, 1972, pp15-20. (9) Fun with Radio, Gilbert Davey, 6th edition, Kaye & Ward Ltd, 1978, pp25-28.