or The ultimate Telrad / QuInsight USB Power / Blinker Mod
I had that "blinker mod" implemented over a decade ago using the trivial LM555 timer IC for my Telrad (you can easily google for that circuit and Telrad integration guides, there are plenty online). But as I have recently acquired the more advanced collimator sight the QuInsight I decided to make a more advanced blinker as well. But it turned out so advanced that I see it frankly opening the IoT era in amateur astronomy!
PrefaceFor several years by now I rarely using my Telrad with its stock power supply (two AA batteries). As simply adding a larger resistor and a micro-USB port-holding PCB I'm powering it from the general USB power bank which is always on the OTA powering my Smartphone and also passively serving as a part of the moving counterweight on the magnet I'm sliding along my Zhumell 12. Having all power consumption standardized to USB 5V is very convenient as power supplies and cables are totally interchangeable can provide plenty of power and there is no need to stock on batteries as you can recharge power banks from a smallish solar panel during day or from the car while driving or at home overnight. Try to find two AAs in the middle of a Chiley desert...
Approaching this mod I've realized that with that much power at hand I can use for the blinker a real SoC circuit (a microcomputer) instead of the dumb timer as I had several former circuits laying around for my GoogleHome IoT projects and none of the latter left in my IC cach anyway. A SoC solution is also much simpler to build as most of the blinking hardware can be implemented programmatically on the chip.
Mechanical designThe QuInsight has quite a roomy battery compartment base with a separate AA batteries holder wired to the LED and the pot body in one corner. It is covered from the bottom with the thin slide-in "drawer" cover. It has four walls available for locating the USB port opening. Ideal enclosure for a microcomputer!
Initially, I had an idea to cut the hole for the micro USB port in the wall of the drawer, so the cable would go straight down along he OTA. That means the SoC PCB need to be mounted on the bottom of the drawer so the USB port at the bottom of its back wall. That means having moving wires going from PCB to the LED and the PCB potentially interfering with the pot body and wires just 4 mm above. Also, I have later designed a very unique scope mount shoe for QuInsight, which is quite close to the focuser (stay tuned for that project blog-post soon) and has a hard stop at the bottom of the shoe which leaves very little room for the USB cable connector casing. These issues are indeed fixable, but seems really sub-optimal.
After some fiddling with the cable and QuInsight in the new shoe on the OTA, I've realized that the side port opening could be much more beneficial, as I can route the cable behind the optical finder shoe above the focuser and completely out of the observer's way behind the OTA. In addition, that would help to avoid any parts interference on the inside and on outside of the battery compartment.
To do that the SoC PCB must be mounted on the "ceiling" of the battery compartment. But the vast majority of the space there is occupied by the rotating "puck" of the reticle module with LED wires coming from the middle. Fortunately, there is enough vertical space there to just rise the PCB above the puck high enough to avoid any interference and alloe free rotation of the module.
After multiple redesigns of the PCB holder targeting the tight fit and minimal excess space occupancy I have been satisfied with this one:
Fig.1 3D design of the SoC PCB cradle (orange on Fig. 2).
This "cradle" has 3 "legs" rising it above the "puck" for about 4mm which is plenty for free rotation with twisting wires. The shape of the leg is pyramidal to minimize the footprint near the walls as the "puck"s well is almost touching walls. There are multiple 1mm screw holes to attach it to side walls with tiny flat-head wood-screws as I want it easily removable and replaceable if the need arises, but I'm using only two of them on the USB port side to keep the board tight against the right (top on the OTA) wall so the USB port is rock solid when accepting the connector.
Printed (in my favorite orange PETG), cleaned the print, slid in the SoC PCB in tight, cut holes for the port and screws in the QuInsight wall using printed template. Assembled. Looks and holds great!
Fig 2. The QuInsight battery compartment with the PCB installed and wired.
Soldered the proper digital out pins to power the LED over 450 Ohm current limiting resistor (blue heatshrink), the Analog Input pin to the potentiometer for manual input commands (yellow). On the image you can see the row of pins bent in to the left. That's just for the ease of soldering wires and to avoid them propping up too much (I had to ditch the idea of making disconnectable joints, too much a hassle, less reliable, and also too close to the vertical space limit). Just 11 solder joints total. The cradle is deep enough to avoid anything getting in over the board and shallow enough to reach out for the in/out soldering points with the iron without removing the board.
On the side it's a bit ugly looking with the screws and the hole:
Fig 3. Usb port and mouting screws on the outside wall of QuInsight
But see what I have in the port:
Fig 4. Magnetic connector and USB cable with magnetic head.
That is the magnetic USB power cord head (the matching magnetic head on the 7' cord you can see nearby is already sensing the mating magnetic field and has 540 degrees of freedom to rotate around for best cable placing). That's an ultimate power connector to deal with in the dark!
Simple, easy, quick, and totally adequate to the task physical mod.
Simple, easy, quick, and totally adequate to the task physical mod.
I have plenty of ideas for the blinker hardware improvement and extension recorded in my GitHub flowchart already. The top five are:
- Add the weather chip (already on the ship from China) to measure temperature, humidity, and air pressure to calculate the dew point conditions notify about them and even control the dew heater (controlled with same PWM as the LED from the SoC) to maintain QuInsight above the dew point.
- Add the LiPO Cell circuit for autonomous controller powering. A typical 2Ah 18650 cell is totally adequate to power the controller for ~30 hours with WiFi On and ~30 days without (with the potentiometer control only, see below).
- Add "the user approaching" sensor (IR radar) to turn on the LED only when I'm near the reticle (along with the "shallow sleep" mode available on the device that could prolong the battery life 2-3 times easily).
- Add the gyro-accelerometer-compass chip. The TPM with QuInsight does wonders for pointing, but I could leverage the Virtual DSC pointing in the day-light in a snap.
- The chip is capable of supporting TFT/OLED screens. I have one amazing but very secret idea for that too.
The brain of the "Uber-Blinker" is a cheap (~$5 shipped) ESP8266 SoC on ESP-12 hat which in a nutshell is a microcomputer with the micro USB port (for power and wired communication), WiFi radio (Access point and infrastructure connectivity), one analog input (to connect a variable potentiometer for example), and several digital in/out multipurpose ports (to connect external digital sensors, LEDs, and sub-controllers as desired). It has some flash storage and some RAM. An extremely capable system, not very power hungry, and very compact (see detailed specs).
But most importantly it has plenty of community support with myriads of interesting projects implemented with it floating around in the Open Domain. My goal was to have a system I could easily tweak in the field all the way to repurposing it from a simple blinker into anything even not astronomy related if I wish, e.g. a connected security perimeter system, a weather station, an EQ platform controller, dew heater controller, etc, right from the observing chair. And that's not just a wish. For several years I've been leveraging the great ESP Basic project for such things development on the go.
The Onboard ESP Basic is a very simple set of instructions following the BASIC language structure (with subroutines and Goto steps) custom-tailored to issue commands to ESP8266 microcontroller from a plain text file saved in the flash memory of the chip. But most importantly, this firmware also creating a simple web server right on the chip which you can access from ANY web browser over WiFi connection (having the chip connected to your home network or directly to your computer/smartphone/tablet/chromebook). Can't you feel opening perspectives yet? They are simply insanely enormous...
My BASIC app for the blinker is just 214 rather short text lines of code total but already implementing the following:
- The fine-tuned for smartphone screens Web server page, with:
- The sophisticated Night Mode CSS color scheme preventing the UI ruining my darkness adaptation (can be reused with any BASIC code drawing the user interface).
- With the link to the microcontroller configuration and programming interface pages for quick access (however they have no Night Mode).
- Simple fully functional user interface BASIC code for the following functions:
- The LED brightness smart controller code, utilizing the PWM to go very low, which:
- Sets the minimal brightness on power connected.
- Provides a slider and two buttons on the screen to control the brightness on the custom non-linear brightness ramp (like 4 minimal brightness levels steps first, then a warning step with no light, then 4 maximum brightness levels) designed to be easily changeable in the code within a single line of values from 0 to 1023 (the PWM modulation ratio).
- The LED blinking smart controller code, which:
- Provides 4 buttons and 2 sliders on the phone screen to control the light pulse parameters:
- Pulse duration time.
- Pulse delay time.
- Setting any slider to 0 disables the blinker.
- The brightness of the pulse is controlled by the above LED brightness feature.
- Calculator-like 9 buttons at the bottom of the screen which allow to launch subroutines with a couple lines of code each, setting the LED brightness and blinking parameters to any combination you might prefer to have one tap of the screen away.
- The code reading the onboard potentiometer position to input data into the controller without the use of the smartphone (reserved for the future smart user input controller implementation which would allow to set modes without the smartphone) for now it can be used to control the brightness same as the slider control on the screen, stepping over the brightness ramp, but on a bit weird tactile ramp, as the pot in the QuInsight has a logarithmic scale).
Fig 5. Smartphone screens of the remote controller. On the right all 9 presets buttons scrolled up.
The user interface (Fig. 5) could be even more minimalist to minimize the amount of light you need to deal with to preserve the eyes darkness adaptation. Buttons are (b / B) to change brightness of the LED, less / more by the non-linear ramp. (d / D) to change the pulse duration, less / more, from 50 ms to 1 sec. (p / P) change blinking period, shorter / longer from 100 ms to 2 sec. 1 ... 9 buttons are for user presets. 1 2 3 are most used visible without the scroll. At the very top you see settings button (will be moved to the bottom below the scroll as it's too bright and better be less accessible). All the buttons are much larger than marking their centers digits/letters so it's hard to miss them (except for "setup" which is hard to tap accidentally). Sliders are good to have to show the current state of the control, but I plan to remove the pulse duration as the shortest pulse seem to work best from my practical experience, any odd pulse durations can be coded in presets. I have the remote code text organized in a way that allows quick removal of any control by simply commenting out a line or two without ruining the rest of the screen layout (the grey bar on the left is the Samsung side-panel drawer handle, sure thing I'm disabling it at night).
Everything works supper stable for days in a row. No overheating or anything. The code is rather trivial and easy to modify on the fly for improvements or changing the blinker behavior as I might all of a sudden see fit in the field. The only issue is that it takes about 30 seconds for the SoC to boot up, connect to the home WiFi hotspot, rise the web server, and start my app which finally brings up the LED On. It's about 10 seconds faster with direct WiFi connection from the phone, still bearable enough as I don't plan turning its power off through the course of the night anyway. Connect and forget.
It took around 10 hours total to build and test the app from scratch (consulting with the ESP BASIC docs often) to my complete satisfaction. The most challenging part was the CSS code for the Night Mode so it would look good on the phone screen.
There are still some ideas to implement for the blinker app though, the top 5 are:
- Add a module saving the last settings of the blinker and presets (see 2) so when turned on it restores what I have been entered / using the last time (good for accidental power failure handling).
- A button to save current manual settings of the blinker under one of the 9 buttons and to add/remove then on the fly, so there is no need to open the code for that, which is a no-no for eyes darkness adaptation (see 5).
- Make a setting to switch the page from night to day mode, as the Night Mode is uber-dark red on black, thus barely visible in the daylight.
- Make a separate Settings page for all settings not needed on the main screen with the option to move them there if needed.
- Modify the ESP BASIC code to allow Day and Night mode switching of the integrated programming/setup interface based on my Night Mode CSS.
My dedicated astronomy smartphone Galaxy Note 4 is always on me when I'm observing with the telescope or without. So it's the obvious remote controller for the "Uber Blinker". But even though you can control it from any browser on your smartphone/tablet most of the browsers have some user interface around the page or popping up here and there as your interacting with the screen to navigate your regular World Wide Web Internet and show you ads. They know nothing about the Darkness Adaptation Religion we are worshiping.
So as a part of this project I have designed a simple Android Web page Viewer app which shows any web page full screen, disabling even system status and navigation bars and with several crucial for Darkness Adaptation preservation options. It works really great already to show the interface of my Uber-Blinker on the phone. As soon as have it polished for the general use I'll be offering it as a part of our DSO Planner app (as the app has the possibility of creating user databases with items having the web link field) and possibly as a separate product on the Android Play Store. Imagine being able to save web pages on your phone and then viewing them without immediately ruining your darkness adaptation at the telescope. Stay tuned!
In addition to that, on all my smartphones I have the Ultimate Android Smartphone Automation App the Tasker. One of the features on its enormous list of features allows drawing a graphical interface of any complexity and binding it to URL calls (web commands). Another Tasker feature allows binding these interfaces to voice commands... So I'm definitely thinking about a set of dedicated controls in my BASIC blinker app convenient to use by voice.
Wow! It won't be long and you'll turn the QuInsight from a simple targeting sight into a fully functional Head-Up Display!ReplyDelete
You are reading my mind! :) The reticle in QuInsight is large enough to replace it with an image on QHD screen occupying ~70% of its half. I can see the bottom part printed as a smartphone holder for just a half of the screen and then an app with two screens one under the collimator, another outside for controls. Instead of the Telrad reticle you can blink it with points or circles which you need to match with real stars. Gyros can be used for rough navigation as well... But OTOH, there is already the Celestron StarSense Explorer...Delete
Just by chance I found a link to Quinsight, when I looked whether there is any modernized Telrad. Rob seems to be the only one who sells something. I have just ordered one.
Apart of him, I found two other designs:
1. This one to do it yourself, with all the design data (and the same reticle as Rob uses): https://www.instructables.com/Wide-Angle-Reflex-Finder-for-Amateur-Astronomers/
2. and this one making Telrad now an electronic device: https://www.reddit.com/r/telescopes/comments/huxvm1/3d_printed_programmable_telrad/
Whe I read your notes, I find there the same ideas as mine and as probably of other guys. What about to replace a fixed reticle by a small LED screen, and use a WIFI connection to your smartphone to programm it?
If you add the gyro-accelerometer-compass chip as you mentioned, you could include coordinates and make it together with and app and a sky map on your phone a "manually operated GoTo". Would you do it? Do you work with Rob together? If not it would be good, because your additional devices might need casing design changes...
I hold a PhD in mechanical engineering, I can do design of small precision parts. But I have no understanding of electronics. Otherwise I would do that development myself...
Regarding the Celestron StarSense Explorer... just a smartphone fixed to the telescope mount. I don't like the idea to fix my smartphone to my telescope tube because of the additional weight. In addition, there is no direct optical view, just the digital screen of the phone. What I propose would combine both.
It could also lead to mechanical simplification, as there would be no need for mechanical adjustments and the glass could be fixed. More simple and more sturdy. The adjustment could be done by moving the reticle on the screen.
By the way, in the firearms branch there already exists something like this, the Mepro Foresight.
Many guys don't get it that a Telrad is not meant to be used for pointing to something I see well (like to point a sniper rifle exactly at the target). There a simple red dot for 7 bucks can do the same. More it has a function like a gun sight for an AA gun - to point somewhere where I don't see anything, using something what I see. In the astronomy it is for star hopping or finding DSO based on the position of stars that I can see, for an AA gun it means to aim "where the plane will be in a couple of seconds". The principle is the same.
But enough for now. What do you think about my ideas? Would you consider that design? And if yes, could I then order one piece?
I could also help with the design, but not in the electronic part.
Best regards from Switzerland
Hi Zack. Thank you for the detailed comment. Sorry for missing it in December as I was traveling, so the Blogger notification was probably lost. Hope you will see my reply here some day.Delete
The short answer is: just gyros alone are not accurate enough for even rough pointing due to the perpetual drift of the zero. Adding a needed magnetometer doesn't improve things much either due to unavoidable telescope metal parts interference. So you need to recalibrate by a star frequently, which is too tedious.
The weight of a smartphone is just a fraction of the weight of any serious telescope, and less than the weight of any modern 100+ deg AFOV eyepiece. So, in practice, that's not an issue. I have my Samsung Galaxy S8 on the selfie stick attached to the rim of my 12" Dob with a heavy duty clamp and a ball head hanging in the air about 60 cm out in front of the secondary mirror, but the counterweight need to be shifted just about one inch farther towards the primary mirror's end to compensate for the imbalance.
Most any small custom screen will have a very rough resolution to be truly accurate with a magnifying lens in the Telrad-like mode. And you cannot draw a reticle just anywhere on that screen due to the spherical aberration causing defocusing, miscollimation, and shape distortions when viewed off the main axis of the collimator objective (or it must be a really complex shape (expensive custom made) lens possibly still with the need of the shape drawing compensation by the app. Which all are not an easy feast, if at all doable given the needed accuracy constraints). So better have a decent screen and a simple mechanical adjustments mechanism like on QuInsight. I didn't notice any flimsiness worth mentioning.
Good points about the Telrad indirect pointing principle being well forgotten. In fact, when applied right, all you need for accurate pointing every time is practice. After 20-30 starry nights you will not only pointing your scope in the matter of seconds but also know most of the major constellations stars and have a good feeling of your instrument dynamics for manual operation, which is also great for manual guiding. Also you will be laughing at consumer-grade GoTo nightmares :)
All these "modern age improvements" are rather for lazy or impatient people who can't gradually learn the art of celestial navigation.
My next iteration with the QuInsight would be reprinting its body to sit on top of the smartphone display showing as a reticle the dedicated app screen with placeholders for bright stars surrounding my DSO target to match the sky view through the mirror with them. No more abstract circles... However, at the moment, I see the StarsenseExplorer-like idea being much more viable for the application, as I have the app prototype already which is working very well with my Galaxy S8 to point at anything in under a minute with about 0.5 degrees accuracy. And that's a purely typical-Android phone hardware and software solution, plus an ordinary (well, very sturdy) $10 off the shelf smartphone photo holder attached to the OTA or the scope mount). What is left to be done is making it working as well on other smartphone models. Which is bummer, but also doable in several ways despite my limited personal resources.
Thank you for your Answer.
Well, I purchased a QuInsight from Rob. Unfortunately it arrived in Switzerland completely broken (glass parts, the base...). Rob was so kind to refund me the cost. Still, I regret not to having the Quinsight in a working condition.
A kind of QuInsight siting on top of a smartphone with a suitable software would be a great thing, I would buy it. There is the advantage of projecting the data into infinity when aiming the stars, unlike the Starsense Explorer. Still, I would purchase Starsense, if only it were available just as a finder, and not only together with a chunky telescope.
However, an available software combining ther sensors of a smartphone for raw alignement, together with plate solving for fine alignement, that seems like a great idea and would be exactly what is needed!
And yes, I know the sky a little. The problem is in a city, where with the eyes you see only 3 mag if ever. Finding DSOs that are "in the middle of nowhere" (unlike M31 or M42) and also not very bright is quite challenging. I can find M81 and M82 in Zurich. OK. But again, finding M64 etc... There a good modern finder would help. But especially - it would help starting astronomers not to get disappointed too early and to enjoy more observing than searching.
Congrats! And a bummer. I think, you can repair it. I've already replaced the glass mirror to a decent 2mm polycarbonate piece and have multiple bases printed (unless you mean the fixed base, which is indeed could be beefier.Delete
I bet, Celestron is just collecting their profits, when all newbies are covered with junk telescopes, we'll see the aftermarket which they will want to profit off as well. So far they are moving it to more advanced telescopes as their device market moving.
The 3m urban sky limit is quite good even with the Telread field coverage. Just employ common eyes darkness adaptation preservation techniques to keep stars well visible (e.g. use a black T-sheert over the head, the eye patch, light screens, etc). Also, the Telrad blinker mod is quite helpful for that as well. What is much more crucial in the light polluted city sky is a decent wide eyepiece magnification matching star chart view. That allows easy FOV stars matching around your target as well as effortless star-hopping around when stuck. I'm using DSO Planner for over a decade with 100% success, thanks to its "Boldness" feature I have incorporated for that. But I can't recommend it anymore as it's a fascist Russia product now.
Hello. Well, the main point again was a modern digital finder. Can a smartphone do it? Well... not so sure. There is SkEye app using smartphone sensors, is however not much accurate. Would be perfect if plate solver were adder for the last accurate phase. Is however not. Also I think projecting the smartphone display into infinity for better aiming would be great. Like into the sights of a war plane. This is all doable today, all the technology exists... only nobody does it. Unfortunatelly I am mechanical engineer with very limited knowledge of programming. Why not to have a really big screen for a finder, why not? It shall not be too heavy, but it can be big. For Dobsons would be ok. By the way, there is a digital gun sight from Meprolight projecting a screen with additional info. So it would be doable also for astronomy.Delete
The FOV of all these military holo sights is laughable in comparison to what we need. And in fact we don't need more info on the reticle, we need it to model the sky mathematically precise and unambiguously.Delete
Most of the phones have indeed inadequate positioning sensors. However, they are within visual pointing sensitivity limits. Plate solving allows to monitor and correct that relatively reliably. So the accuracy of pointing should be on par with most commercial solutions like PushTo but much more reliable and without the need of expensive scope modifications.
Well, having said this, all astronomical reflex finders with the exception of Telrad and QuInsight are nothing else than very cheap versions of gun red dots and have no higher FOV.Delete
In my opinion and experience, there is no need for a help to aim the main scope roughly into the desired object. Whether it is a planet or a DSO, the rough position (+/- a few degrees) is usually known to the observer. With the exception of beginners, but there not the finder but the knowledge is the way. The point is the exact position, in order to get the object into the sight of the main telescope. Using a smartphone, I see no other option to plate solver. And I think there is no need for a fancy bracket with a mirror like the Celestron one. Just the right software. Unfortunately I don't know any. Apart of that one from Celestron. And yes, if there were a display projection into infinity, it would help. Like I think it would help in driving a car and using GPS, not to change the focus from the road to the screen and back.
Ordinary reflex finders are for direct pointing. Their FOV is just about enough to make finding the red dot easier. Indirect pointers like Telrad need a really large undistorted FOV to allow the use of visible stars as far from the target as possible, exactly to help pointing in high Bortle levels skies.Delete
I guess, the confusion is because we are talking about collimators and about plate solving solutions in one conversation. They are hardly intersecting in fact. The plate solving method doesn't need any reflex tech. Only a good camera on the phone.
Well, I have to apologize for messing more topics together. This causes a confusion.Delete
The StarSense Explorer uses a mirror for the camera, it is there just for a better ergonomy for the smartphone position. I assume.
The plate solving method doesn't need any reflex tech? Not necessarily, that is true. However, having that info projected to a big screen when looking at the stars would not be bad. At least I would like to have that.
And yes correct, all red dots are for direct pointing. Whereas Telrad and its improvement the QuInsight are for indirect pointing. On the other hand, the technology is in principle the same. That caused the confusion in our discussion.
However, I would like to see a combination of a Telrad style finder and a digital technology. At least I think it would be worth testing.
That's totally fine, just clarifying for the future.ReplyDelete
I see your point. On a side note though, and to reiterate the initial conversation point: I do have the fully functional plate solving app on my phone which works for me. It doesn't use any mirror, which is indeed making the phone screen control awkward being facing down. However, I've found a solution to that (even several viable options which I'm varying during the night). And that's crucial, as the lack of the aligned mirror is making the system setup easier then Celestron's to reproduce for anyone, so that's a keeper for sure. Now imagine you have some collimator above the screen, I think that will make screen operating even harder. As well as making the task of rigging (reproducing too) such a pointing setup quite hard again too. You will need a collimator matching your phone screen, some casing to hold and adjust both, and so on...
The solution I'm ended up using with that PS system I had in development is simply placing the phone screen in the sky at the length of my stretched out hand. So, to point, I'm simply turning my head to the left from the eyepiece and watching the directional guide for pushing on the screen. On a 6.6" phone screen it looks already very close to the venerable AR view you want, just move your head to align the phone with the sky, using stars you see on the screen :)
And would it be possible to get that app? I would surely be curious to test it.Delete
By now I like my 7x50 straight view finder. Telrad is great for raw indirect aiming, but then doesn't help much for accurate pointing. So I ude both..
Regarding QuInsigt - would be great, unfortunately the base (that integral part of the piece) was smashed to pieces, glass broken and the lense broken... Otherwise the piece makes a good impression, I just wished the base were more robust. Well, Rob answered the base is robust enough... And sure, the transport company had to handle the package very very hard...
I don't know about the app availability for testing anymore (it's the special version of DSO Planner). As I quit the development team because my former coding buddy turned out to be openly pro-fascist (he is living in Moscow and supporting their criminal boss putin). Can't tolerate that, sorry. Perhaps, monitor the app's website for announcements, but I bet the guy will be betatesting among his fascist friends. I might consider taking the endeavor of making my own app for that, but can't tell if or when as I feel largely demotivated.Delete
Also, you can wait for Celestron. They will bring it sooner or later no doubt.
For now I'd suggest just focusing on continuing mastering your FOV ID skills. Even after the push-to (of any kind) you will have to do that in the primary EP of the scope anyway. And the best aid for that is a decent handheld star chart. I'm doing just that with the DSO Planner exclusively as it has the best support for all of those tasks from Telrad to the eyepiece. You can disagree, but all other similar apps for smartphones are not just subpar to it, but simply ill conceived for those tasks in my opinion.
For Telrad, I guess you saw my earlier "TPM" write up already? In fact, if you see at least one navigation star within the Telrad rings vicinity you are all set for several arc minutes pointing accuracy already. Just have Telrad calibrated once on your scope on a good sky and practice for several nights with the DSO Planner Telrad overlay.
By the way, knowing you are into guns (me too) I just ordered: https://www.aliexpress.com/item/2255800867697662.html?spm=a2g0o.order_list.0.0.6fc01802h4AfqS for my hunting shotgun. That mini scope should work with Telrad in the bad urban sky. So you can try the TPM method with that addition. Just leverage your mechanical skills to rig some picatinny rail to Telrad (I'm definitely planning trying that).