{"id":11707,"date":"2016-12-05T10:42:10","date_gmt":"2016-12-05T18:42:10","guid":{"rendered":"http:\/\/rustybolt.info\/wordpress\/?p=11707"},"modified":"2024-05-10T23:20:09","modified_gmt":"2024-05-11T06:20:09","slug":"2016-12-05-small-capacitors-from-twisted-wire","status":"publish","type":"post","link":"https:\/\/rustybolt.info\/wordpress\/?p=11707","title":{"rendered":"2016-12-05 Regenerative Receiver"},"content":{"rendered":"

After I unsoldered the parts from my failed ‘noisy regenerative receiver’ circuit, I decided to build a more conventional regenerative receiver, one that uses a single transistor for the regenerative stage. I chose the circuit from a website that I had found, and saved the schematic. But I forgot to document the URL of the website. So I’ve attached the schematic which has the author’s name and ham call letters to identify it.<\/p>\n

\"image\"<\/a> <\/p>\n

I used the following values for the parts.<\/p>\n

C1 100 nF
\nC2 not used
\nC3 4.7 uF
\nC4 1000 pF
\nC5 27 pF fixed, 4 to 14 pF var. cap in parallel.
\nC6 25 pF mica variable capacitor
\nC7 two 2.2 nF in parallel.
\nC8 5 pF variable capacitor set to max
\nC9 not needed, already in the audio amp<\/p>\n

R1 10k, 25 turn trimpot
\nR2 0 ohms (not used)
\nR3 44k – two 22k in series
\nR4 no value given, used 1k in series with a 5k pot, giving 1k to 6k
\nR5 10k<\/p>\n

L1 14 turns 20 AWG on 3\/8 in. diam. wood dowel – about 0.8 uH.
\nRFC1 33 uH RF bead with several turns threaded through the center hole
\nQ1 I used a C9018 VHF transistor.<\/p>\n

I reused my amplifier and earphone from the nonworking regenerative receiver. The supply is a three AA cell holder, so fresh cells will give a bit more than 4.5 volts.<\/p>\n

I got noise from the regenerative circuit as soon as I powered it up. With a little tweaking, I tuned it, and got noise but received no communications. I did hear bursts of RF coming from my cell phone. The antenna is only about 7 inches long. I think the receiving frequency is not in the CB band. My dip meter showed the coil as resonating at about 27 MHz. I guess I’ll have to make a transmitter that puts out a known frequency in the 27 MHz band. I looked for some schematics of VFOs that hams build and I found one that is supposed to be very stable if it is built properly.<\/p>\n

Update Dec 7 – I mounted most of the pieces on a piece of plywood, and put a piece of sheet metal on it for a front panel. I got the Batteries, audio amp and volume pot mounted. I drilled a hole in the plywood that is the size of the dowel that holds the coil, and I can press the dowel into the hole so that it fits snugly. I have to rearrange some of the parts so they aren’t in the way. The RF part is sensitive to movement, so this ‘breadboard’ should help a lot in making it more stable. I measured the total battery drain at about 2.5 mA.<\/p>\n

I changed the fixed resistor R4 to 1k and a 5k pot in series and mounted the pot on the front panel. I get hiss, but I still haven’t received any signals. After adjustments my dip meter said the coil was resonating at about 27 MHz, but the meter isn’t accurate and is probably off a bit. When the dip meter is on, it quiets the hiss, so I guess that means the regenerative circuit is doing something.<\/p>\n

I have been looking at other regen schematics, and I found that the ones that use a JFET do not need a diode detector, but the others that use a BJT have a diode as the detector. Except for the one I’m experimenting with, which is missing the diode. I think I’m going to have to add a diode somewhere, and I’ll have to do some experimenting to find out where.<\/p>\n

Update 2017-01-22 I’m building another FM regenerative receiver, see here<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

After I unsoldered the parts from my failed ‘noisy regenerative receiver’ circuit, I decided to build a more conventional regenerative receiver, one that uses a single transistor for the regenerative stage. I chose the circuit from a website that I had found, and saved the schematic. But I forgot to document the URL of the <\/p>\n

(Read More…)<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[75,293,74,205],"tags":[294,295],"class_list":["post-11707","post","type-post","status-publish","format-standard","hentry","category-capacitors","category-do-it-yourself","category-electronic-components","category-mechanical-devices","tag-make-your-own","tag-picofarad-capacitor"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/11707","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=11707"}],"version-history":[{"count":17,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/11707\/revisions"}],"predecessor-version":[{"id":11836,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/11707\/revisions\/11836"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=11707"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=11707"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=11707"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}