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VU2ESE Agc circuit
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Hi,
Has any one built Ashhar's agc circuit and had it work? Seems it adds at least 10k ohms between the audio out and the speaker, if I add that much resistance I get no sound out of my speaker. Maybe I don't understand where it is placed. Also in the photo it seems the exciter and collector of the 2n2222 or 2n3904 are switched relative to the schematic. Any help appreciated. I have not tried VK3YE's yet, though it seems it would add at least 4.7k Thanks, Jerry AA1OF Sent from my iPad |
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Gerry,
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"it adds at least 10k ohms between the audio out and the speaker", where are you attempting to install the VU2ESE AGC circuit ?? Both the VU2ESE and the VK3YE AGC circuits act by shunting the audio signal around the volume control, the VU2ESE using a FET as the active shunting element and the VK3YE circuit using an LDR (driven by a LED) as the active shunting element. Neither of these circuits acts directly on the audio signal between the audio output and the speaker. There was an informative post made in the last few months of one of our number who tried both the VU2ESE and the VK3YE AGC circuits. He found that for him the VK3YE circuit was the best/ easiest to set-up and had the most pleasing AGC action. Just search the past posts looking for AGC + VK3YE. Best of luck, Peter VK1XP On 07-06-2017 04:33, ohwenzelph via Groups.Io wrote:
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Hey Peter,
I will check it out. For the vu2ese one I was putting it just before the speaker, I guess it should be before the volume pot. The way I have looked at it they both seem to stick a big resistance right in the audio path. Thanks for the reply. With all the soldering and unsoldering i do worry about how much lead is getting into my brain though... could explain some of my not getting it, I guess. Jer AA1OF |
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Jerry,
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It's OK, we all make dumb mistakes, I've made many in my career, it's how we learn, hopefully. Best regards, Peter VK1XP On 07-06-2017 15:08, ohwenzelph via Groups.Io wrote:
Hey Peter, |
¿ªÔÆÌåÓýFollow up: Ok, the 5-2-2017 revised schematic in the wiki makes it clear where to put the agc circuit (instead of just audio in & audio out. "splain it to me like I'm 5 please") Built per the schematic(ignoring the photo in the mod blog) and put where it is actually supposed to be, the sound actually gets thru!!!! [I do not understand this electronics stuff... sigh..] There was a buzz but I had alligator clip wires all over the place, so forgiving that.? Will try the vk3ye one, sounds like there are a large variety of LDRs.. so results may vary? Did try the anti hiss mod in the "tips and mods" with 'NOTE:?NOT Bitx40 schematic', with 0.01 and 10k from pin 5 to pin 8 of the lm386, but it did not work for me and added a loud 10k hz tone. Sent from my iPad |
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Jerry,
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The LDRs that you are looking for are the ones with the lowest ON (ie; lit-up bright resistance) resistance. The Bitx volume control pot is a 10k unit so if you are going to shunt the audio signal around the pot you will need an LDR with a ON resistance lower than 10k. Have a look on Ebay and you will see a number of LDRs for sale. The trick is to find and read an LDR spec sheet and chose an LDR type with low ON resistance. Here are some I found: GL5528 10 - 20k so too high GL5516 5 - 10k in the ballpark but a bit high GL5506 2 - 5k this looks like the one to go for Check out Ebay the GL5506 sell for US$0.99 for 20 pieces. Shop around you may do better. Regards, Peter VK1XP On 07-06-2017 23:47, ohwenzelph via Groups.Io wrote:
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Jerry,
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I forgot to mention. The LDRs seen to have a peak response (to light) at around 550nm which is red LED light wavelenght, so a plain old red LED is good. On 08-06-2017 19:08, pierre@... wrote:
Jerry, |
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John P
On Wed, Jun 7, 2017 at 06:47 am, ohwenzelph wrote:
Ok, the 5-2-2017 revised schematic in the wiki makes it clear where to put the agc circuit (instead of just audio in & audio out. "splain it to me like I'm 5 please"I'm confused too. I can't seem to find the version of the schematic that you referenced; still trying to find my way around here! So much to digest! I thought I read somewhere that the red wire from the volume control connector should go to the input of the AGG, and the output should go to the volume control where the red wire previously went, but I can't find that again either. Is this correct? Thanks! -- John - WA2FZW |
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John P
On Sat, Jul 8, 2017 at 10:13 pm, John P wrote:
I thought I read somewhere that the red wire from the volume control connector should go to the input of the AGG, and the output should go to the volume control where the red wire previously went, but I can't find that again either.Never mind! I found it this morning the answer is in message #21519. It seems like there are a lot of threads about the VU2ESE AGC circuit. Is there a moderator or somebody that could merge all of them? ? -- John - WA2FZW |
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