Dear likeminded Folks and especially the ones who have built an Aion Xenotron,
There has been a number of Posts on this Forum discussing unsatisfying performance of the Manual range in this build and temporary "Solutions" have been putting bits of Paper between LDR4 and LED4. I have built a Xenotron and have carefully (with the Use of a Frequency Counter and a Spectrum-Analyzer Plugin) explored the Working of the Flanging Side of Things.
I have come to the Conclusion that the actual Problem here are not so much the LEDs but the LDRs.
Aion clearly suggests the Use of LDR NSL-19M51. This LDRs Datasheet suggests an Illuminated minimal Resistance of 5 kOhm. However every single one of those that i've measured goes into a Range of about 50 Ohms when illuminated. That is a factor of about one hundred.
Here are my Obervations:
1.
In it's Original State with the NSL-19M51 as LDR4 (and the specified LED) the clock Frequency of the MN3207 goes actually up to 760 kHz. I seriously doubt that this is the Intention. Yes it could be driven way over its nominal 200kHz (as some Posts on other Forums document) however this would only be possible well with the Use of some 4047 and some Hex Inverter as a buffer but not a lousy 3201. In its Original State (due to the illuminated Resistance of about 50 Ohms) pretty much half of the rotation of the Manual Pot doesnt do much but drive the clock into this absurd Range where delay is about 0.67 msec and requires an adjustment of the bias Pot and still is not usefull at all.
I soldered in a 4.7K Ohm Resistor in Series with LDR4 to pretty much achieve the minimal Resistance here (also what the Datasheet of NSL-19M51 suggests) and this greatly helps to make the manual Range much more useful across its Range. Maximum Dark Resistance is not imporatant because it is in parallell with a 120kOhm Resistor and the resulting clock Frequency at the other End of the Spectrum is about 22kHz which should be the same on every Build without LDR4 having an Influence here.
2.
About LDR2 (and to some Degree LDR1):
LDR2 controls the Level of the dry Signal when the Flanger is active.
Here the Original Manual of the Flange with no Name gives us an interesting Hint:
It says that the the Point of deepest Flange is pretty close to the Extremes of the Action Pot. Using a noise generator and a Spectrum Analyzer Plugin it becomes obvious that with the "Original" Configuration with the NSL-19M51 and the specified LED deepest flanging cannot be achieved at all because the dry Signal is to loud as a Consequence of LDR2 actual illuminated Resistance (only if you put pieces of Paper between LDR and LED). This can clearly be observed on the Spectrum Analyzer with white Noise.
I soldered in also two 4.7 kOhm Resistors in Series with LDR2 and LDR1 (to make that symmetrical) and that remedied that Situation tremendously.
Now as to why the NSL-19M51 that I got (from Musikding and a separate Order from Mouser) dont perform as their Datasheet implies I don't know.
What could be very helpful would be if someone with an original Lovetone Flange could use a Frequency Counter to measure the Max Clock Frequency at Minimnal Manual Setting. I unfortunately don't have one.
So as a final Tip: if you built a Xenotron and are unsure about its Performance try soldering 4,7kOhm Resistors in Series with LDR1 LDR2 LDR4. 4.7kOhm ist just a value that I took based on the LDR Datasheet but but maybe an 8.2kOhm might work as well or even better. LDR3 is not important since it only opens the feedback Loop that can be calibrated with the use of the Trimpot.
Maybe my Findings can be a Help to some other People who had unsatisfying performance of their Xenotron Builds.
Regards
Philipp
There has been a number of Posts on this Forum discussing unsatisfying performance of the Manual range in this build and temporary "Solutions" have been putting bits of Paper between LDR4 and LED4. I have built a Xenotron and have carefully (with the Use of a Frequency Counter and a Spectrum-Analyzer Plugin) explored the Working of the Flanging Side of Things.
I have come to the Conclusion that the actual Problem here are not so much the LEDs but the LDRs.
Aion clearly suggests the Use of LDR NSL-19M51. This LDRs Datasheet suggests an Illuminated minimal Resistance of 5 kOhm. However every single one of those that i've measured goes into a Range of about 50 Ohms when illuminated. That is a factor of about one hundred.
Here are my Obervations:
1.
In it's Original State with the NSL-19M51 as LDR4 (and the specified LED) the clock Frequency of the MN3207 goes actually up to 760 kHz. I seriously doubt that this is the Intention. Yes it could be driven way over its nominal 200kHz (as some Posts on other Forums document) however this would only be possible well with the Use of some 4047 and some Hex Inverter as a buffer but not a lousy 3201. In its Original State (due to the illuminated Resistance of about 50 Ohms) pretty much half of the rotation of the Manual Pot doesnt do much but drive the clock into this absurd Range where delay is about 0.67 msec and requires an adjustment of the bias Pot and still is not usefull at all.
I soldered in a 4.7K Ohm Resistor in Series with LDR4 to pretty much achieve the minimal Resistance here (also what the Datasheet of NSL-19M51 suggests) and this greatly helps to make the manual Range much more useful across its Range. Maximum Dark Resistance is not imporatant because it is in parallell with a 120kOhm Resistor and the resulting clock Frequency at the other End of the Spectrum is about 22kHz which should be the same on every Build without LDR4 having an Influence here.
2.
About LDR2 (and to some Degree LDR1):
LDR2 controls the Level of the dry Signal when the Flanger is active.
Here the Original Manual of the Flange with no Name gives us an interesting Hint:
It says that the the Point of deepest Flange is pretty close to the Extremes of the Action Pot. Using a noise generator and a Spectrum Analyzer Plugin it becomes obvious that with the "Original" Configuration with the NSL-19M51 and the specified LED deepest flanging cannot be achieved at all because the dry Signal is to loud as a Consequence of LDR2 actual illuminated Resistance (only if you put pieces of Paper between LDR and LED). This can clearly be observed on the Spectrum Analyzer with white Noise.
I soldered in also two 4.7 kOhm Resistors in Series with LDR2 and LDR1 (to make that symmetrical) and that remedied that Situation tremendously.
Now as to why the NSL-19M51 that I got (from Musikding and a separate Order from Mouser) dont perform as their Datasheet implies I don't know.
What could be very helpful would be if someone with an original Lovetone Flange could use a Frequency Counter to measure the Max Clock Frequency at Minimnal Manual Setting. I unfortunately don't have one.
So as a final Tip: if you built a Xenotron and are unsure about its Performance try soldering 4,7kOhm Resistors in Series with LDR1 LDR2 LDR4. 4.7kOhm ist just a value that I took based on the LDR Datasheet but but maybe an 8.2kOhm might work as well or even better. LDR3 is not important since it only opens the feedback Loop that can be calibrated with the use of the Trimpot.
Maybe my Findings can be a Help to some other People who had unsatisfying performance of their Xenotron Builds.
Regards
Philipp
