![](\"https:\/\/i0.wp.com\/www.bartola.co.uk\/valves\/wp-content\/uploads\/2018\/01\/Tail-CCS-v02-1.jpg?w=840\")
<\/p>\nRecently I’ve spent some time designing some PCBs for my own use and why not to share them as well to the DIY audio community. Currently I have a flexible CCS board for anode loads and a tail CCS, which is the one I will write about on this post.<\/p>\n
I came up with a 3cm x 3cm PCB board which provides the maximum flexibility for a tail CCS circuit. Below is the diagram:<\/p>\n
<\/p>\n
There are 2 options to go here: BJT or MOSFET. There are some minor differences, but the same board can accommodate both circuits, which is pretty handy.<\/p>\n
Let’s start with the MOSFET version. This one is the classic ring of two but with a MOSFET (M1). The board can accommodate TO-220 as well as TO-92 and SMD versions. The protection zeners. Z1 and Z2 will ensure you can use a HV supply at +B. R2 is the gate stopper and can be either through hole or SMD. You can set the CCS current with the resistor R3 or if variable current or precise adjustment is needed you can use instead a trimpot (P1) and R4 in series. This CCS is very tight and has a good temp-co as well as stability considering changes to +B. Given the MOSFETs have lower transconductance compared to the BJT, the output impedance won’t be that high, but will be high enough for most purposes. I considered implementing a cascode stage, but wanted to keep the board small and simple. The temp-co is negative, which means the current will drop when temperature rises. MOSFETs on the other hand are available at higher voltages, so this stage may be useful to implement when higher negative voltages across the CCS are required (e.g. 100V or more)<\/p>\n
The BJT option is an improved design. The NPN can be any of your choice: TO-220 or TO-92 and can accommodate low voltage to even high voltage devices (e.g. 400V) . In most of the applications you will probably use voltages below 50V at the tail CCS. The stability (both on temperature as well as on variations of the power supply) is improved thanks to the shunt voltage reference. U1 can be either the LT1009 or the ZR431. Both TO-92 or SMD options are available on the board.<\/p>\n
Well, I still need to do some further tests on the prototype PCBs but so far so good. I think this tiny PCB is very flexible and can be used in many circuits like cathode follower stages as well as LTPs, etc.<\/p>\n
If there is some interest out there, I may make the PCB available.<\/p>\n","protected":false},"excerpt":{"rendered":"
Recently I’ve spent some time designing some PCBs for my own use and why not to share them as well to the DIY audio community. Currently I have a flexible CCS board for anode loads and a tail CCS, which is the one I will write about on this post. I came up with a … Continue reading “Tail CCS PCB prototype”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[5],"tags":[],"class_list":["post-7081","post","type-post","status-publish","format-standard","hentry","category-valves"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2r2tK-1Qd","jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/7081","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/comments?post=7081"}],"version-history":[{"count":0,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/7081\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=7081"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=7081"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=7081"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}